Fix bug:range() is not same in py3.x and py2.x

in python3.x, there is no method named xrange(),
it has replaced by range(),which is equal to xrange() in python2.x.
so we must fix this issue.we use six module to fix this issue.

Change-Id: I9cee3f0df2d8abbf6f66d7c5a3a0fed98df622e8
Closes-Bug: #1268439
NSX: lower the severity of messages about VIF's on external networks

Set the message to INFO as there is no error to recover from or
something bad about to happen. The only place where this occurs
is during the setup of probe interfaces in DevStack.

Change-Id: I2310af00676e508646783ce769a8830ab0b9308f
Cisco Nexus: maximum recursion error in ConnectionContext.__del__

If DevStack is configured for the Cisco Nexus plugin, the following
error is observed:

Exception RuntimeError: 'maximum recursion depth exceeded' in <bound
method ConnectionContext.__del__ of
<neutron.openstack.common.rpc.amqp.ConnectionContext object at
0x403a3d0>> ignored

The root cause of the problem is that the Cisco Nexus plugin's
PluginV2.__gettattr__ method, a model object is being passed
as a value for a unicode %s format mod. Because the neutron server
has "lazy gettext" (deferred interpretation of unicode objects) enabled,
this causes many layers of recursive calls to deepcopy.

The fix is to pass a string object for the unicode %s mod field.

Change-Id: I0a07a0ab417add68e44cb1bca722cb0b4a71205b
Closes-Bug: #1286565
Added config value help text in ns metadata proxy

Change-Id: I9d59e902cf9ed89e29d93b29912c87f2bad73c7c
Closes-Bug: #1215270
Fix duplicate name of NVP LBaaS objs not allowed on vShield Edge

Duplicate name of LBaaS objs such as pool/vip/app_profile is not
allowed on vShield Edge, so here a name convention is needed to ensure
name uniqueness on the edge side.
Closes-Bug: #1257225

Change-Id: I953610d0389a78aa01f378c2ff4931d8c74413ea
Fix typo in lbaas agent exception message

Change-Id: Iec2a5e02d40f73e4576ed853577a6a9f85e49e67
Closes-Bug: #1295187
Add enable_security_group option

Using noop driver to disable security group is confusing.
In this commit, we introduce enable_security_group in server side.

DocImpact
UpgradeImpact

Implements bp: security-group-config-cleanup
Related-Bug: 1112912
Change-Id: Ice44a4e2a519c64e613eeb24372de46726473339
Avoid creating FixedIntervalLoopingCall in agent UT

Set polling_interval to 0 to avoid creating LoopingCall
in loadbalancer agent tests, dhcp agent tests, linuxbridge agent tests

Change-Id: Ib6edbc11feba402a4c2f19b7d6833b49879ee626
Closes-Bug: #1288079
Merge "NSX: lower the severity of messages about VIF's on external networks"
Merge "Avoid creating FixedIntervalLoopingCall in agent UT"
Merge "Add enable_security_group option"
Merge "Fix duplicate name of NVP LBaaS objs not allowed on vShield Edge"
Merge "Added config value help text in ns metadata proxy"
Merge "Fix typo in lbaas agent exception message"
Merge "Cisco Nexus: maximum recursion error in ConnectionContext.__del__"
Merge "Fix bug:range() is not same in py3.x and py2.x"