Added Repo to Maven Central (AAR Build)

Now Foldable Layout library is available in Maven as AAR Build. URL : https://oss.sonatype.org/content/repositories/snapshots/com/github/alexvasilkov/

To add this maven dependency to any project, 

        compile 'com.github.alexvasilkov.FoldableLayout:library:1.0-SNAPSHOT'

This line should be added to build.gradle file in 'module' level.

Thanks for this wonderful library!