Logging detail when attach interface failed

When attach interface failed, there isn't any detail for
error info. Change the log level to exception to get more detail.

Change-Id: If531c32357dbb002a3e92e4ca559eeb7f6ab6d2d
Closes-Bug: #1373761
Remove native security group api class

There are native security group api classes define in the v2 and
v2.1 security_groups extension. Those classes in two extensions
are same. So remove the duplicated code, move those exception raising
into the base class.

Change-Id: I5e62ec8236e9d0e9601be652df7b8abf1828fbad
Better error message when check volume status

When debug the code, the cinder volume status checking code return
the error message, but without which volume is wrong and detail.
This patch add volume uuid and detail in the message.

Change-Id: I043f7b956b7e56ea5eb7e4ff9c9023fd607f2358
Port assisted-volume-snapshots extension to v2.1

This patch ports assisted-volume-snapshots to v2.1 and make v2 and v2.1
share unit test cases.
This patch addes a schema to do the input validation for snapshots_create
The differences between v2 and v3 are described on the wiki page
https://wiki.openstack.org/wiki/NovaAPIv2tov3 .
Partially implements blueprint v2-on-v3-api

Change-Id: I5b7be1de8ac2628a287897dcc5ca0eaf7a8957a2
Merge "Port assisted-volume-snapshots extension to v2.1"
Merge "Better error message when check volume status"
Merge "Logging detail when attach interface failed"
Merge "Remove native security group api class"