Code cleanup on NoteObserver and Notify

Fix 500 error when project is empty

Added project has_one :last_event assoc. Fixed tab line-height after font-awesome. Increased projects per page on dashboard

Use Font Awsome for icons

add shared repository support

Fix issue close and reopen button text and styles

Small fixes for editing files

Refactor tree views and improve consistency

Remove redundant branch labels from MR form

Fixes #1525