Merge pull request #96 from oroulet/master

Implement Republish service call
Update README.md
Merge pull request #98 from oroulet/master

improve python api and examples, diverse fixes
check pointer in stop method of opcuaserver
rename OPCUAServer and RemoteClient to UaServer
and UaClient. to be consistent
more commenting of python examples
add methods to converts python/opcua datetimes
convert with microseconds precision
add support for datetime in variant python wrapper
automatically convert datetime from python to c++
NOT from c++ to python since we may lose information
add test for python datetime