Add pkg-config support.

(in-line update: add libcgmanager.pc.in.in  - serge)

Signed-off-by: James Hunt <james.hunt@ubuntu.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
tests: install all under /usr/share/cgmanager/tests/

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>