refactored git version handling in cmake #869

Conflicts:
	CMakeLists.txt
moved generated headers in devel tarball #869

Conflicts:
	src/mongo/CMakeLists.txt
changed what gets packaged by default by cmake #869
fixed cmake errors with git versions #869
fixed cpack file name #869
set CPACK_PACKAGE_NAME in the hopes that it will set the tarball names
properly for enterprise builds #869