Bug 1034600 - [Messages] Suggestions list is badly located. r=julien

* Recipient suggestions container moved to more appropriate place;
* Recipient suggestions now occupy all possible space minus heights of the app header and message "To" field.
* ```.contact-list``` styles are cleaned up a bit.
I'm really not sure it takes more memory: the function is still in memory even if you remove the listener !

The drawback is more code. When I have the choice, I prefer to have less code.