Use default rpc_response_timeout in unit tests

During running of tox the system can timeout on slower systems.
We have seen this occur in our internal tests and have seen
better results when we increased the api timeout from 15 to 60
seconds.  This can be used until faster hardware is availale
or a better fix is proposed.  Andrew Laski first proposed
this fix.

Closes-Bug: 1311778

Change-Id: I33da328e7bea8fbdde3f01ee0147b4c5a3a278d2
(cherry picked from commit dead965a4398d5093426cf21d2875b55a451e671)
Fix the wrong dest of 'vlan' option and add new 'vlan_start' option

* Allow to specify vlan tag when create nova network, the dest of vlan
option should be 'vlan' instead of 'vlan_start'
* Provide new option 'vlan_start' when create nova network
* test case is updated.

DocImpact
Closes-Bug: #1288609
Change-Id: I8dd858e4cf17d8f689613554d1fbc3e56f220886
(cherry picked from commit e251535eaa7c6a564eddb9218de177c9bea656bb)
Merge "Fix the wrong dest of 'vlan' option and add new 'vlan_start' option" into stable/icehouse
Merge "Use default rpc_response_timeout in unit tests" into stable/icehouse