[voicecall] Remove accidentally committed .pro.user.
[voicecall] Remove QtSingleApplication from voicecall-ui.

This also involves making voicecall-ui boosted.

There is some remaining work in using the precreated QDeclarativeView, but this
is a solid start for now.
Merge pull request #4 from rburchell/master

Remove QtSingleApplication usage from UI