Hide avatar

Hide the avatar in the conversations list screen
for a more descriptive feel. Can be enhanced to
messages screen later.

PS 2 : Reoder Settings a bit

Change-Id: I1cd93c80d0d096159c74287aa3d1dc252b9a3728

Conflicts:
	res/values/strings.xml
	res/xml/preferences.xml
Fix number picker

Number picker was always HOLO_LIGHT due to hardcoding
by Google. We solve it using the settings reference.

Change-Id: I13238bcc70746cefdadded6544dd7360ad7a6289