fakevirt: return hypervisor_version as an int instead of a string

The compute_nodes.hypervisor_version type in the database is an integer
not a string. This is only caught in postgres and not MySQL. Changing
the fakevirt driver to return the proper type allows for the
test_virt_drivers test to make check this for all drivers it currently
tests.

Change-Id: I25e4dba855b954a2451bced9a53172b51eb47238
Fix HTTP response code for network APIs and improve error message

This patch corrects the http response codes for network resources to be
consistant with other resources by returning a 400 instead of a 404
if the desired resource is not found.

This patch makes the following api changes:

v2-api: NetworkNotFound now returns 400 instead of 404 and improved error
        message which network was not found instead of
        'The resource could not be found'.

v3-api: PortNotFound and NetworkNotFound now returns a 400 instead of a 404.

Closes-bug: #1245696
DocImpact

Change-Id: I66eb0c0ab926e0a8d1e2c9cfe1f7fd579ea3da21
Added a new scheduler metrics weight plugin

The new metrics weigher can compute the weight based on the compute
node host's metrics data. The to-be weighed metrics and their
weighing ratio are specified in the configuration file as the
followings:

    metrics_weight_setting = name1=1.0,name2=-1.0

The final weight would be name1.value * 1.0 + name2.value * (-1.0).

This is part of the blueprint utilization-aware-scheduling.

DocImpact

Change-Id: Ib3e68505e6d4d8f6d67b54c5f00de3e1c172738c
Sync rpc fix from oslo-incubator

Sync the following fixes from oslo-incubator:

ef406a2 Create a shared queue for QPID topic consumers
e227c0e Properly reconnect subscribing clients when QPID broker restarts

Closes-bug: #1251757
Closes-bug: #1257293

Change-Id: I917c7a6e5cb64c6383e74d0fb6e095ad17d4d478
Merge "Added a new scheduler metrics weight plugin"
Merge "Fix HTTP response code for network APIs and improve error message"
Merge "fakevirt: return hypervisor_version as an int instead of a string"
Merge "Sync rpc fix from oslo-incubator"