Add new route for updating user passwords #318

[hedleysmith]

Adds a new route to the REST API PATCH /v1/userPassword/:id which expects a user id as the only argument and {password: [newpassword]} as the only body field of the request.

Discussed in #318

[christiansmith]

Sorry for the delay in looking at this. The PR looks good overall. Only thing I'd consider changing is the route path to something like /v1/users/:id/password.

[hedleysmith]

Using /v1/users/:id/password makes complete sense to me, have updated the route and tested

[christiansmith]

Thanks @hedleysmith. Great to have this new feature!