Hide quote of original message

When answering a carteggio message, normal email clients quote the
original text. This commit hides the quote in the conversation view and
instead shows three small dots at the end of the message. If the user
wants to see the full message with the quote he must tap on the message.
Improved robustness of code that creates destination address

If the contact name contains the @ character the previous code was
crashing.
Do not ring every time mailbox is checked

When pending messages are present the notification rings each time the
mailbox is checked. This commit removes this behaviour.
Improved notification handling code

Fixes a bug that prevented opening main activity when new messages
where notified and solved two warnings due to usage of deprecated APIs.
Improve receipt notifications

Now we put a text body in the receipt so that people that use clients
that do not handle receipts can understand what they are. We also fix a
bug in the formatting of the receipts.
Improved regular expression to find quotes in emails
Use conversation icon on actionbar of conversation activity
Bumped version to 5
Merge pull request #11 from lokeller/next-release

Bug fixes and improved usability