Initial provider NSA discovery client.
NSI topology client.
`TimeSampBridge`: don't return `null`.

The implemented interface specifies that null cannot be returned. Return
an empty string instead.
`PhysicalPort`: removed `equals` and `hashCode. Added `toString`.
Use NSI topology as inventory.

The user can now select the type of physical port (E-NNI or UNI) when
allocating the port.

Changed all edit actions to use the `edit` word instead of `update`. Use
`POST` instead of `PUT` to avoid some strange Jetty 9.2 JSP errors.