TestlinkAPIClient does not accept optional argument 'transport' for proxy configuration

[lczub]

proxy configuration, introduced with #36, only works with api class TestlinkAPIGeneric
the api class TestlinkAPIClient does not accept optional arguments like transport.

tl_helper = TestLinkHelper(proxy='PROXY-71')
myTestLink = tl_helper.connect(TestlinkAPIClient)

Traceback (most recent call last):
  File "D:\Projekte\Testlink-Python-API\Issues\20150601_issue55_getProjects\getProjects_from_demo.py", line 42, in <module>
    myTestLink = tl_helper.connect(TestlinkAPIClient)
  File "D:\Projekte\git\TestLink-API-Python-client\src\testlink\testlinkhelper.py", line 143, in connect
    return tl_api_class(self._server_url, self._devkey, **kwargs)
TypeError: __init__() got an unexpected keyword argument 'transport'

[lczub]

Travis build passed for Py27 - Py34, but failed for Py26.
Seams, that the new unit tests test_connect_with_proxy needs a special handling for Py26