misc: fix contact request UI issues

- switch between "conversations" - "invitations" smartlists according to call origin
- "Accept Request" button from msg's view header: hide on contact accepted, set on view load according to userType
- correct requests smartlist item selection on tab switch
- accept incoming call from pending contact makes conversation permanent

Gitlab: #74

Change-Id: Iadfef0d7e4032002d8007a4f18a9eae27f7ba230