Sign up methods to be tested.
New menu option: signup.

There is some problem in the maths, because the server says it's ok but
login doesn't work from Android app nor from webapp.
Signup protocol coded. UI next.
Raw json error messages shown.

A bit of refactoring too, sendM1 much simpler.
Error messages fetched directly from api message.

This has the problem of localized messages. irc log questioning:

May 8th 2014
08:12 <@parmegv> mm, I was thinking... I was rephrasing the error messages given by our api during authentication
08:13 <@parmegv> I thought why should I rephrase it and think twice
08:13 <@parmegv> so now I'm just "pretty printing" the error message given by the api
08:13 <@parmegv> but that has a problem: they aren't localized
08:14 <@parmegv> would implementing a localized version of our error messages be useful?
Automatically log in.

Functionality copied to the Release build.
Cancelling a failed signup/login stops progressbar
Signup option in login dialog.
Merge branch 'feature/signup-support-#5586' into develop