Merge pull request #36 from solispauwels/master

Spanish translation
fixed bug delete if notifications are empty
Merge pull request #37 from solispauwels/master

fix error
Merge pull request #38 from claroline/delete-users

fixed bug delete if notifications are empty
reply to a specific post
custom installer
checkstyle
fix bug additionnal installer
Merge pull request #41 from claroline/posts-reply

reply to a specific post
Fixed updater bug (closes claroline/Claroline#606)
Replaced tabs by spaces
Font Awesome icons update