Merge pull request #48 from oroulet/master

bugfix
Implementing addin variabled to the object. Added ability to set/get variable value.
Added test for accessing object type.
Build fix: libopcuacore is dependent now on libopcuaprotocol.
Implemented variable most part of variable element interface. Added ability to access variables of object by relative path.
Implemented updating of server time in the address space.
Fixed DateTime calculating, converting.
Creating Server object inside OPCUAServer.
Merge pull request #53 from treww/master

Server Object publishes current server time. Fixed DateTime calculations.
small fixes
Merge branch 'master' of github.com:FreeOpcUa/freeopcua
set server timestamp in node.cpp