Adding in new parts to ConcurrentLib

New ConcurrentObjects header in ConcurrentLib contains concurrent
objects. Right now there is only a ConcurrentCounter which works nicely.
It uses the new C++11 atomic template type to make sure access to certain
variables have atomic access. This way you can have X threads working on
the same counter and incrementing it. Pretty cool!

Updating CMakeFiles to build new library and install headers. concurrent-
garth app also 'uses' the libraries to make sure linking and all that is
okay. Everything seems to be working fine.