[FTE] Fixed some jshint errors

- Tried to fix all the errors for FTE js
- Left the tests for another PR
- Unable to fix some of them, advice is more than welcome:
  - wifi.js - two objects declared, one call the other and viceversa, so one is called before being declared.
  - customizers/default_contacts_customizer.js - function created within a loop.
  - tutorial_steps.js - possible strict violation, not sure about the cause.