Make v2.1 API tests use v2 URLs(test_[f-m].*)

Most v2.1 API tests are using v3 URLs, because there didn't exist
a fake router for v2.1 at the time. However, now the fake router
exists.
This makes v2.1 API tests of use v2 URLs for testing v2.1 API as
v2 compatible API for test_[f-m].*.py.

Partially implements blueprint v2-on-v3-api

Change-Id: I0ec295685473659de9c34a8b1ec4fbc9ec793019
Make v2.1 API tests use v2 URLs(test_[r-v].*)

Most v2.1 API tests are using v3 URLs, because there didn't exist
a fake router for v2.1 at the time. However, now the fake router
exists.
This makes v2.1 API tests of use v2 URLs for testing v2.1 API as
v2 compatible API for test_[r-v].*.py.

Partially implements blueprint v2-on-v3-api

Change-Id: I5388c9e6547e80746af7978642b5dc0c7ad70d0e
Return HTTP 400 if use an in-use fixed ip to attach interface

When posting an 'attach interface' request to Nova with an in-used fixed ip,
Nova need to return HTTP 400, instead of HTTP 500, in order to inform the
user to correct the fixed ip in HTTP request. This code change will take
effect with Neutron only.

Change-Id: Ic5fe49ef0966c981756b5c6e1bf755e587a95ac1
Closes-Bug: 1363901
Replace outdated oslo-incubator middleware

It has graduated to oslo-middleware

DocImpact

Change-Id: I6dbf77ee56b8008ed286e1b7c367a8a94f005498
Merge "Return HTTP 400 if use an in-use fixed ip to attach interface"
Merge "Replace outdated oslo-incubator middleware"
Merge "Make v2.1 API tests use v2 URLs(test_[f-m].*)"
Merge "Make v2.1 API tests use v2 URLs(test_[r-v].*)"
Merge commit 'refs/changes/41/127941/3' of git://gold.eng.hq.xensource.com/git/github/openstack/nova into tmpbranch