Cisco VPN with in-band CSR (interim solution)

Currently, the Cisco VPN drivers use two routers for the proof of concept
solution. A Neutron router provides access to the public and private
subnets, and a Cisco CSR (out-of-band) provides the VPN tunneling.

The end goal is to integrate the Cisco VPN drivers with the Cisco L3
routing plugin being developed (as a separate blueprint), allowing an
in-band CSR to be used as a Neutron router for VPN functionality.

This commit provides an incremental approach to that goal, by modifying
the Cisco VPN drivers to be able to dynamically obtain CSR info from
an INI file, instead of statically reading the INI file at start-up.

A CSR VM can be created out-of-band (or in-band using Nova) and the INI
file can be updated with the router info. Then, the Cisco VPN driver
can use that information (dynamically) to create IPSec connections.

Once the Cisco L3 router plugin is available, the INI file will be
removed, and two calls to the plugin will be used to obtain the needed
router information, for an integrated solution.

The main advantages are:
    - Dynamically use the CSR for VPN.
    - Less manual intervention and setup.
    - Easy migration to final solution.
    - No dependency on the Cisco L3 router plugin implementation.

Note 1: The INI unit tests are moved from device driver to service
        driver and modified.

Note 2: I added a unit test for deleting IPSec site-to-site connection,
        which was missing (pass).

Note 3: For more details on the change, you can view this Google Doc:
        http://goo.gl/DXir8c

Change-Id: I307fc79952e3e12a0f77679ac1fc2b314fa63684
Partially-Implements: blueprint cisco-vpnaas-with-cisco-csr-router
Merge "Cisco VPN with in-band CSR (interim solution)"