emojicons

After all that freaking work, I discover a library exists already for the iOS emoji pack. Apache 2.0 license (https://github.com/rockerhieu/emojicon/blob/master/LICENSE).

At the very least, a start. Also removed preference to set smiley to enter key (will always be enter key) since there's now a persistent emoji toggle.
I feel like this entire diff block is out of place in ConversationActivity. Is there no way to make a component that abstracts all of this away?  The shared preferences stuff strikes me as a real hack.