Removed password show/hide function.

Moved account saving confirmation to checkbox.
Removed unused imports
Added prototype AccountPicker (the delete buttons do not do anything yet, need to fix layout so it looks less awful). Choosing an account currently "logs in" directly with chosen account without going back to the login activity.
Account picker now functional, can either pick account (resulting in login) or delete stored account. Currently the back button on phone is used to navigate back to login screen. Highest prio now is to integrate with stuff that calls the actual github api (both to use accounts and to verify that accounts really exist).
Cleanup + proper backbutton behaviour in MainActivity.
github account requests - not tested yet
Merge branch 'master' of https://github.com/Sajfer/EDA397-Group6 into gitlog
get credentials and get users repositories are added.