Improve login flow

[thibaultmol]

Somehow I noticed when I had my phone reinstalled and had to sign in again was that there might be something that could be improved when it comes to logging in.

Steps:

• fresh app install
• you download, make a change somewhere
• you want to upload. it prompts you to login
• you login
• you land on this screen that shows how many changesets and messages you have
  .... and then you're there.....
  I feel like an enduser might be confused as to what to do now.

So maybe 'if the oauth was started because user clicked on the upload button' then it should either close that screen or provide a big button that closes it and goes back to the upload ui