Renamed the 'Overview' tab to 'User account'

- It was perceived, that the 'Overview' tab was asking a user to change it's password,
  when instead it is the only possible action in the case that the user is not an admin.
  To prevent further confusion, we renamed the 'Overview' and moved the tab just before the 'Logout' link.
  The default view for non admins is now set to the 'Translate' tab rather than the 'User account'.
Admin area now displays the current git commit hash.

- The hash is displayed at the right side of the topMenu,
  and also links to the github page for the according commit.
- Closes #14