This patch improves how the trunk plugin supports future
segmentation types and how it can handle multi-driver
deployments where each driver may have its own set of
supported segmentation types. It does so by:
a) removing the existing segmentation type registration mechanism;
this has become superseded by how drivers advertise their
capabilities and register themselves with the plugin.
b) introducing a new compatibility check that makes the plugin
fails to load in case of conflicts: for multi-drivers environments
a common set of segmentation types must be found for the plugin
to load successfully. In case of single driver deployments,
a driver can bring its own segmentation type.
Partially-implement: blueprint vlan-aware-vms
Change-Id: I0bd8b479c07945c65e14d4b59dfbcc1bc9a85a88
fb5c043d0d