Added link to the blog post in README.md
Update README.md
.gitignore modified

Added .idea/ and /app/build to the file
build.gradle updated

- bump compileSdkVersion to 20
- bump buildToolsVersion to 20
- added lintOptions
- bump Android support library to 20.+
- added crouton library as a jar file (due to an error: 'module version 1.8.5.
depends on library but is not a library itself')
Merge pull request #1 from mmBs/master

Added changes to build.gradle, .gitignore and README.md