0.16.0 New firestore user data structure

[blonsky95]

Each document in users has a uid. If we want to send a file to them, we need to get the uid first, to do that we do a "where" search and get a ref to the document that holds that username, and then update that id.

Test sending exercises

Do forgot your password functionality https://stackoverflow.com/questions/42800349/forgot-password-in-firebase-for-android

Then make sure post and get your online copy of exercises works.

[blonsky95]

Test sending exes - DONE

forgot password - done

make sure post and get online works - should be working - only a doc id reference change

[blonsky95]

it should be noted that the business logic, aka all the auth checks and registering should be done from a view model, so a login signup viewmodel - not closing until that done

[blonsky95]

Ready to test new viewmodel contained business logic with only observers for interaction, there is no non ui code related in the View. Check if works and then proceed to home page!!!!!!!!!!!