FD-04 Add social share button gem

Facebook share button seems not to work
FD-04 Change share buttons implementation to user js API's

Remove social-share-button gem
Add Facebook, Twiiter and Google plus javascript API's
Add a test in user profile
FD-04 Improve share buttons and add share icons

Add follow buttons to home page
Create a help page (used for testing for now)
Remove socia-share-button's gem files
TODO: Make Facebook and Google Plus popup appear on the center of the screen
FD-04 Center popup window when using sharing icons
Merge branch 'master' into FD-04_SocialNetworks-Sharing
Merge pull request #10 from Dzeta/FD-04_SocialNetworks-Sharing

FD-04 social networks sharing