Merge pull request #5 from miminar/master

concurrency issues fixes
introduce ScopedSLPHandle (RAII)
really release GIL until the function's end

Previous line released the GIL and immediately re-acquired it.
Merge pull request #6 from miminar/workaround-gil

Fix previous threading fix.
fix CIMInstance::getitem() return value by reference
bump release version to 0.3.0
set namespace for each CIMInstance when WBEMConnection::enumerateInstances() is called
add property/parameter name to Pegasus::TypeMismatchException
create keybindings when not None in CIMInstanceName::asPegasusCIMObjectPath()
refactor exception handling in WBEMConnection's CIM methods
bump release version to 0.3.1
refactor CIMConstants CIM errors

Due to C++ optimization of level 2, lmiwbem can't be imported because of missing symbols.
some autotools cleanup
introduce distutils as secondary build system
drop second level of configuration in setup.py
simplify WBEMConnection::createInstance()

Based on Devchandra's input. When creating a new CIMInstance, no CIMInstanceName is needed for construction of the object. Namespace can be passed via optional parameter of CreateInstance(). Previous API is unchanged due to PyWBEM compatibility.
fix README.md to reflect the proper steps for generating setup.py
introduce WBEMConnection::request_accept_languages
fix documentation build paths
fix (Build)Requires and typos