Porting SecurityGroup related controller into v2.1

This patch port SecurityGroup, ServerSecurityGroup and SecurityGroupAction
controller into v2.1 security_groups extension.

This patch just move the v2 code into v2.1 and share the unittest. The other
v2.1 related fix and improvement will be addressed by subsequent patchset.

Partially implements blueprint v2-on-v3-api

Change-Id: I93951ce677b74ebed7db1b2fff1f788344806dba
Pull extra_specs_ops tests from test_host_filters

First in a series of patches to uncruft the 2000+ line
test_host_filters.py unit test file. This patch moves the
extra_specs_ops tests into its own test file.

Change-Id: I200265be6fbc2df1877f01531f443cff8337cebf
Port update method of cloudpipe_update to v2.1(v3)

This patch adds couldpipe_update's `update` method to cloudpipe controller
add validation schema to cloudpipe, have v2 unit test cases shared between
v2.1 and v2.

Partially implements blueprint v2-on-v3-api

Change-Id: Ibf39d7fa7301bcba6e259ae88a73c20f64b7fc36
Merge "Port update method of cloudpipe_update to v2.1(v3)"
Merge "Pull extra_specs_ops tests from test_host_filters"
Merge "Porting SecurityGroup related controller into v2.1"