Feature/bower

Add bower repository,
Add reademe in markdown,
Add gitignore.

For init bower, after merge with master, go into your repo and past this
command :

bower register Collapsible https://github.com/juven14/Collapsible

When the bower repository is init the readme badge work with version and
you apear in  http://sindresorhus.com/bower-components/

Have a nice day.