adding coversalls support to travis
Using py.test --cov
Installing pytest-cov
Added test command to setup.py that runs pytest
Excluding rtd branch from coverage in qt_compat
removed qt_compat from coverage

because each travis job imports either PySide or PyQt, coveralls
thinks some jobs are missing coverage in qt_compat, which in overall is
not true

also, removed dummy __main__ at the end of basics
adding test for waitForWindowShown
Adding coverage badge to README
Merge branch 'coveralls'