On create_volume flow get rid of host parameter

On manager create_volume flow save host parameter to volume_ref immediately
when create volume_ref and remove host parameter from other tasks.

Change-Id: Ifc672741c317112b084a076ca65c11c5d0290930
vmware: intermittent failure in test_vmware_vmdk

There was a race condition between the two Event() objects being
created within loopingcall and Retry in api module. Did away with
the Event object in Retry and used loopingcall the right way.

Change-Id: I2534bad9294747fcd618ba3634abb01ceef92213
Updated from global requirements

Change-Id: I60e217d361a71b2c7518aff98b5530e689d838c5
Merge "vmware: intermittent failure in test_vmware_vmdk"
Merge "On create_volume flow get rid of host parameter"