Parameterize OPENSTACK_HYPERVISOR_FEATURES settings

Horizon can provide GUI support for some hypervisor specific features.
However the setting to enable can_set_moint_point is currently hardcoded
in the local_settings.py.erb template rather than being
parameterized, making it impossible for users to enable support for
these functions. This patch adds a parameter hash to enable users to
select how they want to configure Hypervisor features and sets default
values to match the old hardcoded settings to maintain backward
compatibility.

Closes-bug: #1271635

Change-Id: Id73b9986e561f1dc7557ae725518ec7694fc0da2
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Merge "Parameterize OPENSTACK_HYPERVISOR_FEATURES settings"