Merge pull request #23 from jpetrell/master

Fix warnings and duplication in voicecall code
[voicecall] Improvements to ofono plugin.
Merge pull request #24 from martinjones/master

[voicecall] Improvements to ofono plugin.
[voicecall] Handle starting without a VoiceCallManager interface present.
Merge pull request #26 from martinjones/master

[voicecall] Handle starting without a VoiceCallManager interface present...
[voicecall] On startup notify clients of ongoing calls.
Merge pull request #28 from martinjones/master

[voicecall] On startup notify clients of ongoing calls.
Provide emergency status through telepathy voice call plugin