Compression

Add compression support.

1. Add UI parts and Account option
2. Add ZLibInputStream - an InflaterInputStream with a fixed available method
3. Add ZLibOutputStream - an DeflaterOutputStream with partial flush support (method was hidden till API level 18, it's now "unhidden" and available since nearly forever)
4. Add an ability to get the Input/Output Streams (needed to wrap them inside an ZLib Stream)
5. Add a minimal fix to UIHelper: I have some contacts in my roster without an empty name... This crashed Conversations