Implement Account Manager

[eyedol]

Use Android Account Manager to handle user authentication for the part of the API that requires users authentication

[eyedol]

@mrl-gt Ping. Anything I can look at? I know you were working on this sometime back

[pdmholden]

Is anyone working on this? If not, I'd be happy to give it a try.

[eyedol]

@pdmholden @mrl-gt was looking into it. We realized it was quite tricky to use the account manager to handle authentication because of the different Ushahidi deployment out there. So we decided to take a different approach and save the credentials using Preferences.

@inoran Did some preliminary work base on this approach. He used the old HTTP client we were using before. See his commit here https://github.com/inoran/Ushahidi_Android/commit/account_auth.

Perhaps you could pick up from his work?.

[pdmholden]

Will do.

[pdmholden]

Let me confirm what needs to be done:

1. Switch the current WebClient login mechanism to use the API instead.
2. Store the user's credentials on the phone.
3. The user will still use the WebClient to access the admin features of their deployment.

Have I got everything right?

[eyedol]

@pdmholden Correct.

Yes, they will use the WebClient to access the admin features. We can then use the stored credentials to login via the WebClient so the user shouldn't have to type their credentials to login.