Add EMC VMAX/VNX support as a provider for cinder

- Add EMC attributes
- Create cinder_emc_config.xml when EMC driver is used.
- Installs appropriate packages when EMC driver is used.
- Add tests for new cinder_emc_config.xml
- Add tests for changed attributes in existing cinder.conf
- Add tests for package installs

Change-Id: I5a44e3626784814f57e15a43ce459a4d36d31c6b
Implements: blueprint emc-cinder-provider