Add .gitignore for Gradle/IntelliJ build artifacts

.gitignore

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..bc250d0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.idea
+**/build
+**/.gradle
+**/.intellijPlatform