Disable TSO on all systems

Even on RHEL7 + OSP5, there is an issue on TSO/GSO. So we need to ensure
that it's disable also on RHEL7/CentOS7 systems.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
identity: disable trove by default

Trove (Database as a service) is still experimental and should be
disabled by default to avoid error with current default configuration.

This patchs does it by adding a new parameter trove_enabled (False by
default) and only create Keystone endpoint if this parameter is at True.

It also avoids to see the Database panel in Horizon by default.
Travis: add QA for Puppet 3.6, 3.7 and 3.7.1

Add more versions of Puppet in the QA process.
Merge pull request #621 from enovance/disable-trove

identity: disable trove by default
Merge pull request #618 from enovance/tso-rh

Disable TSO for all systems
Merge pull request #622 from enovance/travis-puppet

Travis: run QA on Puppet 3.{2,6,7}
Refactor all Neutron configuration

Refactorization from puppet-neutron:
* use neutron::agents::ml2::ovs in a new class: cloud::network::vswitch
* include this class automatically in network & hypervisors classes.
* allow some flexibility in agent configuration and open the class to
  eventual other drivers. Currently, only ML2 with OVS is supported.
* Cleanup cloud::network to avoid useless code.
* Refactorize provider networks usage.
* make cloud::network::controller plugin agnostic
* make cloud::network plugin flexible with ML2 by default
* Deprecation of somes parameters in cloud::network with a warning but
  no backward compatibility.
* Update unit tests.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>