Drop unittest in multiconnection tests (#654)
Drop unittest in multiconnection tests (#654)

* Convert multi-connection read tests to pytest.

* Replace assertEqual in multi-connection tests.

* Convert multi-connection read/write tests to pytest.

* Convert multi-connection layer creation tests to pytest.

rbuffat/Fiona,rbuffat/Fiona,Toblerity/Fiona,Toblerity/Fiona