Cisco VPNaaS and L3 router plugin integration

This completes the blueprint effort to integrate the Cisco VPNaaS
drivers with the Cisco L3 router plugin for a VPN solution that
uses an in-band Cisco CSR (versus out-of-band, as is currently).

The VPNaaS service driver is modified to no longer read router
configuration from an INI file, but instead, will query the L3
router plugin for this information. The config loading logic is
removed. The router information is transformed and passed to the
device driver for use by the REST client.

The L3 router plugin now provides two methods to provide the needed
router and hosting device info. In addition, the template and
snippets used to provision the Cisco CSR are modified to have the
needed VPN settings and to change the VRF configuration to the new
style to support VPN REST API calls with VRF info.

The VPNaaS device driver was modified to provide the VRF name as
part of the URI for several VPN REST API calls, as needed for this
solution. The device driver uses the additional VRF and interface
information that is provided by the service driver.

The unit tests were updated to reflect the usage of VRF names, and
the new logic for checking router information.

Change-Id: Id2a59673f99c52a43556a8cc389afbc97bf41249
Implements: blueprint cisco-vpnaas-and-router-integration
Merge "Cisco VPNaaS and L3 router plugin integration" into stable/junoplus