CMakeLists.txt: Switch to pull source from git repository. ATLASSIM-3139....

CMakeLists.txt: Switch to pull source from git repository. ATLASSIM-3139. Tagging as AtlasCLHEP-00-00-12-06 (AtlasCLHEP-00-00-12-06)

	* CMakeLists.txt: Switch to pull source from git
	repository. ATLASSIM-3139
	* Tagging as AtlasCLHEP-00-00-12-06

2016-10-27  John Chapman  <John.Chapman@cern.ch>

	* CMakeLists.txt: fix typo in source url.
	* Tagging as AtlasCLHEP-00-00-12-04
	* Tagging as AtlasCLHEP-00-00-12-05

2016-10-21  John Chapman  <John.Chapman@cern.ch>

	* Test out CLHEP 2.2.0.4 without thread_local variables.
	* Tagging as AtlasCLHEP-00-00-12-03

2016-09-05 Antonio Limosani <Antonio.Limosani@cern.ch>
	* Branch to revert to old version of CLHEP see ATLASSIM-2898 in CMake build
	* Tagging as AtlasCLHEP-00-00-12-02

...
(Long ChangeLog diff - truncated)