PIN for mobile devices

* If you haven't PIN, create one.
* Auto loggin with you PIN

#### To-Do

- [x] Front-end flow to enter and create a new PIN
- [x] Encrypt, read and save pinData to localstorage (using pinService.js)
- [x] ~~Add set/change PIN on Profile.~~
- [x] Logout should remove pinData
- [x] Add flag to use only on mobile
- [x] When check() returns true, change 'logout' option from sidebar menu to 'lock'
- [x] optimize for mobile screen

Fixes #1939 and #1938
variable name should be `askForPin`, not `setPin`