implemented processContextToken -- see #4
Changed should_be_a(int) to should_be_an_integer()

for python3 compat reasons
implemented importSecContext and exportSecContext -- see #4
updated readme requirements to reflect landing of cython refactor
added implementation and tests for acquireCredImpersonateName -- see #31
added some things to type_wrappers to facilitate the s4u class development
fixed some bugs in type_wrappers.py
s4u support working...
fixed up some of the type wrapper code
s4u support working -- helper class in place, fixes to type wrappers to facilitate