We used to put `try / except ImportError` around oslo lib imports
to support both the `oslo_lib` and `oslo.lib` name patterns.
It is now useless since the newer versions of these libs all support
the `import oslo_lib` pattern.
Tested on CentOS 7 with the OpenStack Liberty repository.
Tested on Ubuntu 14.04 with OpenStack Liberty CloudArchive repository.
Change-Id: I7a147586d7a933506df62e34424e5fc57b3ff503
Sem-Ver: bugfix
30a67fac85