[libngf-qt] Client: emit eventPlaying() on play()

Relates NEMO#684
Use qmake variable to deal with the -qt5 suffix

Relates NEMO#684
Add configure() qmake function

Relates NEMO#684
[tests] Initial commit

Note: when building with Qt5, the warning
"QDBusConnectionPrivate::disconnectRelay called for a signal that was not
found" is issued a number of times - this is fixed in recent Qt versions.

Relates NEMO#684
Workaround QSignalSpy issues with QDBusInterface

1. QDBusInterface relies on QObject::connectNotify() to connect the
   D-Bus signal immediately when QObject::connect() is called.
   QSignalSpy uses internal version of QObject::connect() which does not
   call connectNotify(). This issue is fixed as a side effect of the fix
   to the second issue -- otherwise it would be necessary to invoke
   connectNotify() explicitely upon SignalSpy construction.
2. TestBase::waitForSignals() uses combination of SignalSpy and
   QEventLoop to wait for signals.  It connects the signals to
   QEventLoop::quit(). When used together with QDBusInterface, it is
   usually too late to connect -- that is why the signalEmitted() signal
   exists.

Relates NEMO#684
Do not set OBJECTS_DIR & MOC_DIR qmake variables

Using variables like these makes usage of `lcov' tool impossible. Please
consider using qmake's support for shadow building instead:

  cd build/ && qmake .. && make

Relates NEMO#684
Add 'coverage' make target

Relates NEMO#684
Merge pull request #4 from martyone/master

Add tests