Make device ID field editable on device page.

[Trek Hopton]

Issue #355 is a prerequisite.

Once sensors and actuators are not reliant on device IDs (names), we should add the ability to change the device ID.

Currently the ID field is greyed out after creation of a device in VidGrind’s device page. It should be changed so that it can be updated like the other editable fields.

[Alan Noble]

Implemented in https://bitbucket.org/ausocean/vidgrind/commits/bea431c9115f59f5c25a3d2b84cb7714b47fccb7