Create ServiceReconfigureRequest / Task model classes

In support of service reconfiguration, add request and
task classes to support the upcoming workflow.

http://bugzilla.redhat.com/show_bug.cgi?id=1077424
Add support for service reconfigure

In support of PaaS-style use-cases where CFME services
are utilized to drive automation-driven provisioning, being
able to reconfigure an existing service with new parameters
is a requirement.  In support of this, services can now be
flagged as reconfigurable, which will give the user the
ability to modify the service parameters via the service
dialog.  Once submitted, the reconfiguration request will
use the existing approval process before invoking the assigned
custom automation to perform the reconfiguration steps.

https://bugzilla.redhat.com/show_bug.cgi?id=1059834