Rename nova.compute.instance_types to flavors

First step in removing references to instance_types. Rename instnace_types.py
and update references to it. We currently use instance_type and flavor as
synonyms, to reduce confusion we are picking one. We are going with our own
terminology, flavors.

renamed:    nova/compute/instance_types.py -> nova/compute/flavors.py

Partially implements bp flavor-instance-type-dedup

Change-Id: I9dc04cf311aa8813be4f5329f23729d2c43cae6d
Fixes mock calls in Hyper-V test method

Fixes bug: #1177605

This patch adds missing mocked calls to the test method
test_spawn_nova_net_vif_no_vswitch_exception implementation.

Change-Id: I115e2e081ef1273c78de1bba1414002d30eaa574
Merge "Fixes mock calls in Hyper-V test method"
Merge "Rename nova.compute.instance_types to flavors"