Clean up Cisco plugin config parameters

Change-Id: I3095f6aa0aa182592bd939ec59bac1820f15676f
Fixes: bug 1201537
Fix auth issue in get_instance_host

_get_instance_host was attempting to use the
admin username and password with the user's
tenant, which leads to 401 auth errors from
Keystone when attempting to determine the
instance host from nova.

This patch reads the admin tenant from the same
place as the username and password and uses that
instead. It also removes the keystone call that
was used to determine the tenant_id from the name,
since that is no longer needed.

DocImpact grizzly

Change-Id: If7ab8df24f8a727b458a780af8909e4cc6e1d0eb
Fixes: bug 1202462
Prevent possible server list damage in BigSwitch plugin

The old failover logic for the BigSwitch plugin modified a
list of controllers as it tested them. If the code for one
thread unexpectedly raised an exception or died, the global
server list could lose a server permanently.
This patch addresses that by flagging servers as failed instead
so the global server list is never modified.

Fixes: bug #1200022

(cherry picked from commit 3732f022778a7c4a47c58029ae77e32a0a4a6ee9)

Conflicts:

	quantum/plugins/bigswitch/plugin.py

Change-Id: Id2dcb820ef9f62fd03e3215bff3345e56c78afe2
Added check for fixed_ip in  add_router_interface

Change-Id: I255e7eda5aa1b7b4644014386ae66f1ebd7c732f
Fix: #29
Signed-off-by: Rossella Sblendido <rossella@midokura.com>