Fix up 'add to blacklist' button behaviour

- Don't crash in landscape, as button isn't present in landscape layout
- Only show it for incoming calls with number (it makes no sense to
  blacklist outgoing calls, and calls without number can't be
  blacklisted on a per-call basis anyway)

JIRA: CYAN-865
Change-Id: Ie98e09abc4f4e62e67ccf12322e2a0cea0e26d60
Fix option description to match behaviour.

Change-Id: I12102b706f9e1b9735b6d0c525c4605de4c2724c
JIRA:CYAN-868

Conflicts:
	res/values/cm_strings.xml