chore(npm): improve ignore list (#60)

diff --git a/.npmignore b/.npmignore
index bd0573e..e02b299 100644
--- a/.npmignore
+++ b/.npmignore
@@ -1,18 +1,4 @@
-demo/
-
-# CI service configurations
-.travis.yml
-.appveyor.yml
+.*
 appveyor.yml
-
-# Testing, code coverage, and linting
-.eslintignore
-.eslintrc.yml
-
-# Git
-.git
-.gitattributes
-.gitignore
-
-# Github
-.github
+demo
+tests