Fix authentication

[kyle-kingsbury]

This PR addresses a few things. in configuration->General->General Settings, changing the machine name was producing an uncaught exception because it was attempting to use an edison specific function in fabmo/network/linux/raspberry-pi/index.js. Also, there were some references to beacon which we removed a while back. Removed them.

Configuration->Users->Change Password was not working at all, nor was it allowing admin to change other users password. Any user can now change their own password, admin is the superuser and can change anyones password. Users that are assigned as admin can add users and change their password, but cannot change the superusers password. For testing:

• Logged in as admin, changed own password, logged out and logged back in with new password
• Logged in as admin, added a new user, logged out and logged back in as that user
• Logged in as admin, changed password of existing user, logged out and logged back in as that user with new password
• Logged in as user, added new user, logged out and logged back in as that user
• Logged in as user, added new user, changed their password, logged out and logged back in as that user with new password

This PR fixes #1014 and the "no user" exception found in issue #1081.

Ran the dev checks and master branch of fabmo/fabmo-api-tests. All tests passed.

[RobMackie]

looks good.

[RobMackie]

ran the same tests you ran (or very close to them) on my machine. I created 2 new uers, changed the password of a user as a user and as a superuser, then logged in as a user and ran the normal devchecks. All went well. It's nice that users work.