Added support for std::condition_variable
Fixes #1 on branch with condvars support
Perfect forwarding of the constructor arguments
ConstAccessor class added
Common code for Accessor and ConstAccessor classes moved to AccessorBase class.
Conditional variables support implemented without exposing internal lock guard field.
Type of the mutex can be set now for the SharedResource template
Merge with condvars_support

Conflicts:
	include/SharedResource.h
	tests/main.cpp
Merge conflicts resolved