[RFC0027] CLI command "update-route" to manage generic per-route options

[Dariquest]

RFC

CLI Support for Generic Per-Route Options

Introducing a new cli command 'update-route', which allows updates to route resources.
Extending the API of the Route to contain generic options map.

$ cf update-route -h
NAME:
   update-route - Update an existing route.

USAGE:
   cf update-route DOMAIN [--hostname HOSTNAME] [--path PATH] [--option OPTION=VALUE] [--remove-option OPTION]

EXAMPLES:
   cf update-route example.com -o lb_algo=round-robin
   cf update-route example.com -o lb_algo=least-connections
   cf update-route example.com -r lb_algo

OPTIONS:
   --hostname, -n      Hostname for the HTTP route (required for shared domains)
   --path              Path for the HTTP route
   --option -o         Set the value of a per-route option, key-value pairs, repeat to set multiple options
   --remove-option -r  Unset a previously set option

SEE ALSO:
   create-route, map-route, routes, unmap-route

Why Is This PR Valuable?

Allow users to manage per-route options via the CLI instead of having to talk to the API directly.

Applicable Issues

GitHub Issue

How Urgent Is The Change?

No urgency

[Dariquest]

Closing this PR and opening the same one in the CF repo cloudfoundry#3328