chore: fix grammar and remove duplicates from .gitignore (#30)

diff --git a/.gitignore b/.gitignore
index c5218e3..0cd3d06 100755
--- a/.gitignore
+++ b/.gitignore
@@ -13,7 +13,6 @@
 
 # Gradle
 .gradle
-build/
 !/tools/build/
 
 # Python
@@ -38,7 +37,6 @@
 .idea
 *.class
 *.iml
-out/
 
 # .zip files must be explicited whitelisted
 *.zip
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ab1fd94..3087b78 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -20,7 +20,7 @@
 
 # Contributing to Apache OpenWhisk
 
-Anyone can contribute to the OpenWhisk project and we welcome your contributions.
+Anyone can contribute to the OpenWhisk project, and we welcome your contributions.
 
 There are multiple ways to contribute: report bugs, improve the docs, and
 contribute code, but you must follow these prerequisites and guidelines:
@@ -49,7 +49,7 @@
 list to see if your issue has already been raised.
 
 A good bug report is one that make it easy for us to understand what you were trying to do and what went wrong.
-Provide as much context as possible so we can try to recreate the issue.
+Provide as much context as possible, so we can try to recreate the issue.
 
 A good enhancement request comes with an explanation of what you are trying to do and how that enhancement would help you.
 
diff --git a/README.md b/README.md
index d2f7f0b..66651c5 100644
--- a/README.md
+++ b/README.md
@@ -64,7 +64,7 @@
 
 ### Managing dependencies
 
-If your action needs external dependencies, you need to provide a zip file including your source and your cargo file with all your dependencies. The folder structure is the following:
+If your action needs external dependencies, you need to provide a zip file including your source, and your cargo file with all your dependencies. The folder structure is the following:
 ```
 |- Cargo.toml
 |- src
diff --git a/gradle/README.md b/gradle/README.md
index 14842f1..fc28d4d 100644
--- a/gradle/README.md
+++ b/gradle/README.md
@@ -41,14 +41,14 @@
 
 ### Test
 
-To run tests one uses the `test` task. OpenWhisk consolidates tests into a single `tests` project. Hence the command to run all tests is `gradle :tests:test`.
+To run tests one uses the `test` task. OpenWhisk consolidates tests into a single `tests` project. Hence, the command to run all tests is `gradle :tests:test`.
 
 It is possible to run specific tests using [Gradle testfilters](https://docs.gradle.org/current/userguide/java_plugin.html#test_filtering). For example `gradle :tests:test --tests "your.package.name.TestClass.evenMethodName"`. Wildcard `*` may be used anywhere.
 
 ## Build your own `build.gradle`
 In Gradle, most of the tasks we use are default tasks provided by plugins in Gradle. The [`scala` Plugin](https://docs.gradle.org/current/userguide/scala_plugin.html) for example includes tasks, that are needed to build Scala projects. Moreover, Gradle is aware of *Applications*. The [`application` Plugin](https://docs.gradle.org/current/userguide/application_plugin.html) provides tasks that are required to distribute a self-contained application. When `application` and `scala` are used in conjunction, they hook into each other and provide the tasks needed to distribute a Scala application. `distTar` for example compiles the Scala code, creates a jar containing the compiled classes and resources and creates a Tarball including that jar and all of its dependencies (defined in the dependencies section of `build.gradle`). It also creates a start-script which correctly sets the classpath for all those dependencies and starts the app.
 
-In OpenWhisk, we want to distribute our application via Docker images. Hence we wrote a "plugin" that creates the task `distDocker`. That task will build an image from the `Dockerfile` that is located next to the `build.gradle` it is called from, for example Controller's `Dockerfile` and `build.gradle` are both located at `core/controller`.
+In OpenWhisk, we want to distribute our application via Docker images. Hence, we wrote a "plugin" that creates the task `distDocker`. That task will build an image from the `Dockerfile` that is located next to the `build.gradle` it is called from, for example Controller's `Dockerfile` and `build.gradle` are both located at `core/controller`.
 
 If you want to create a new `build.gradle` for your component, simply put the `Dockerfile` right next to it and include `docker.gradle` by using