Allow building of RPMs with CMake

- Don't install .la files
- Fixed packaging/rpm/package.mk for adaptation

Change-Id: I5a1d046d83d9548e66c7aea1571af38af1fa0371
Reviewed-on: http://review.couchbase.org/42769
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>