* desktop/CMakeLists.txt: Translate the appdata file rather than just
installing it directly.
* desktop/geary.appdata.xml.in: Rename from 'geary.appdata.xml', make
name, summary and description translatable.
* cmake/FindIntltool.cmake: Add a CMake command for the appdata file.
* po/POTFILES.in: Include geary.appdata.xml.in.
* desktop/CMakeLists.txt: Fix name of Elementary Contractor desktop file
and disable Desktop file validation for it since it doesn't actually
validate.
* cmake/FindDesktopFileValidate.cmake, cmake/FindIntltool.cmake: Don't
assume XDG Desktop files are named ".desktop" - they aren't for
Elementary's Contractor. Require callers to pass the full name in, fix
call sites.
Geary can now be configured to notify of new mail at startup. When
the user logs in, Geary will autostart with a hidden window and
notify of new mail as usual. When Geary is formally executed by
the user the Geary window simply appears.
In this mode, if the user closes the window Geary will return to its
hidden state. Quit must be used to close the process.
