[buteo-sync-plugins] Use QTEST_MAIN instead of own main.cpp file.

Fix build and libs linking.
[buteo-sync-plugins] Disable contacts storage unit tests.

Contacts backend reader manager was change by a16776a290b3d0881b3072bc13bd190b49b61e1d
to use non privileged db, since the writer is using privileged db test can't be used for
this setup, this commit disable them.
Merge pull request #34 from nemomobile/fixTests

[buteo-sync-plugins] Use QTEST_MAIN instead of own main.cpp file.