Ensure that headers are utf8, not unicode

Although the api.openstack.wsgi.ResponseObject converted the headers to
utf8 strings to comply with RFC for HTTP this was not enough, since some
responses that contained unicode strings were returned, causing an error
when running nova behind an http server like Apache. This change ensures
that headers are always an utf8 encoded string.

Closes-Bug: 1254017

Change-Id: I980326f1f15907bf57060acdd132011254289079
Allow run_image_cache_manager_pass to hit db slave

Deployments that have a slave_connection configured can offload
read queries there. For deployments with no slave behavior
remains the same.

Change-Id: Ic443913883d80bdbc95385f8d3e21c0d855bb7db
Partially-implements: blueprint periodic-tasks-to-db-slave
Define "supported_instances" for fake compute

Allow fake computes to deploy images with hypervisor_type
defined and set to "fake" and by extension to be used in
multi hypervisor_type deployments.
Mixing fake and "real" computes on the same OpenStack
deployment allows to create many fake instances and some
working instances for testing applications on top of
OpenStack (ie: fake instances for stress tests, working
ones for functional tests).

Closes-bug: #1260771
Change-Id: Idc337c4a7ed024f236ca2b60d91e2c30f7d54536
VMware: Only include connected hosts in cluster stats

Currently the driver includes all hosts connected to VC
(including disconnected hosts) when calculating available
vcpus. The patch enforces that the reported available stats
only include resources of hosts that are connected to the
VC.

Note: A host can be connected to a VC, but have a disconnected
host state

Change-Id: Iba9d80f894cc2b7471a7f9c87b7367fd93bacb48
Closes-Bug: 1257998
Remove V3 API XML entry points

Removes the entry points defined in setup.cfg for
the V3 API XML. These are no longer called.

Partially implements blueprint remove-v3-xml-api

Change-Id: I1fd516b5a01f1ce2b4d42320594616a49b66952d
Merge "VMware: Only include connected hosts in cluster stats"
Merge "Ensure that headers are utf8, not unicode"
Merge "Allow run_image_cache_manager_pass to hit db slave"
Merge "Define "supported_instances" for fake compute"
Merge "Remove V3 API XML entry points"