Adding support for dynamic API libraries

I am new to Python so excuse me if my code is not very Pythonic.
Some tests are excluded for dynamic libraries not implementing get_keyword_arguments because the error message comes from Python and will not be the same as when RF "knows" the arguments and issues the error.

BTW the three tests stating "Fails with ExpatError when server runs on Jython 2.5" also fail for me on Python 2.7.2 as well (Win7).