Add notify type preference.
Differentiate highlights and mentions.
Use hashCode to generate PendingIntentBroadcast

This let us get mutliple notifications with distincts PendingIntent
Remove highlights functionality, since Flowdock has removed it.
Merge pull request #6 from tomitm/types

Add notify type preference.
Check if ImageLoader is already initialized.
Breakout initialize into it's own method, so that it's more maintainable and early exit makes sense.