Cisco VPN device driver - support IPSec connection updates

Provides support for IPSec connection updates and state changes. To do
this, the configuration of the connection is maintained, when the
connection is created. This is checked against the current settings, at
sync time, to determine whether a configuration change (as opposed to a
state change) has occurred.

If there is a change to the configuration detected, then the simple
approach is taken of deleting and then re-creating the connection, with
the new settings.

In addition, if the admin state of the connection changes, the tunnel
will be taken admin down/up, as needed. Admin down will occur if the
IPSec connection or the associated VPN service is set to admin down.
Admin up will occur, if both the IPSec connection and the VPN service
are in admin up state.

Added REST client method to allow changing the IPSec connection tunnel
to admin up/down (effectively doing a no-shut/shut on the tunnel I/F),
based on the above mentioned state.

Modified UTs for the support of IPSec connection update requests (used to
throw an "unsupported" exception), and to check that the configuration
and state changing are processed correctly.

Updated so that tunnel_ip is set in device driver, rather than hard
coding, and then overriding in REST client. Since device driver has the
same info, this will fit into future plans to obtain the info from
router, vs reading an .ini file. Revised UTs as well.

Change-Id: I184942d7f2f282c867ba020f62cd48ec53315d3e
Closes-Bug: 1303830
Merge "Cisco VPN device driver - support IPSec connection updates"