In VMAX driver version 3.0, SMI-S has been replaced with
unisphere REST. This is porting Compression from SMIS to REST.
See original https://review.openstack.org/#/c/400824/ for more
details
Change-Id: I2d7cda0b5856ec5c3c1ca7df4f2ad93936f15b57
Partially-Implements: blueprint vmax-rest
