Fix config opts for Storwize/SVC volume driver.

Removed the "vtype" option which did not work in the driver, and
added the "easytier" option. Added another check to _check_flags
and made sure -warning flag is passed properly. Added unit tests
to check all option variations.

Fixes bug 1049446.

Change-Id: I135ed85ad1b9d60e6a8cc406aa49360e0f080039

etc/nova/nova.conf.sample

@@ -1999,9 +1999,6 @@
 # storwize_svc_volpool_name=volpool
 #### (StrOpt) Storage system storage pool for volumes
 
-# storwize_svc_vol_vtype=striped
-#### (StrOpt) Storage system volume type for volumes
-
 # storwize_svc_vol_rsize=2%
 #### (StrOpt) Storage system space-efficiency parameter for volumes
 
@@ -2018,6 +2015,9 @@
 # storwize_svc_vol_compression=false
 #### (BoolOpt) Storage system compression option for volumes
 
+# storwize_svc_vol_easytier=true
+#### (BoolOpt) Enable Easy Tier for volumes
+
 # storwize_svc_flashcopy_timeout=120
 #### (StrOpt) Maximum number of seconds to wait for FlashCopy to be
 ####          prepared. Maximum value is 600 seconds (10 minutes).