#3 - Deleting entries via AJAX works again.

Moved to using @PathVariable to identify the entry to delete. 

Refactored use of Optional in GuestbookController.removeEntryJS(…) as a plain if is more readable in this case. Left the Optional code in there to show it for comparison.
Merge branch 'bootstrap' of https://github.com/st-tu-dresden/guestbook.git into bootstrap
included 'use strict' in guestbook.js
now we only shoot our toes off
removed unused index.html
new formatting
tabs, tabs everywhere
added missing semicolons
tidied messages.properties
modified guestbook.html to use new msg.properties
removed unused success parameter in success handler