Handle oauth_problem

[scompt]

Fixes #144 by handling the case where an OAuth provider returns the oauth_problem parameter. See here for what this parameter can mean.

[VilemKurz]

Theoretically in a case user presses cancel there should be no alert. ShareKit should behave the same way as if cancel of the whole view is pressed -> SHKOAuthView itself would make a check of the return value, and if user cancels it would call [self cancel].

BUT

LinkedIn uses user_refused (which can be used on other errors too?) instead of permission_denied.

I have looked at other services, and it seems there are many, which do the same (myspace, StatusNet, ..) . I think the best solution could be to incorporate your fix (for various oauth_problems) + in SHKOAuthView make a check if the user cancelled (user_refused + permission_denied) - if yes, call [self cancel] and do not show the alert. If you agree with this, I will make a separate pull request for that.

+1 for this pull request

edit: permission_denied seems to have different meaning, so I would leave alert for this one.

edit2: your fix should also cure #121 and maybe other not yet discovered crashes too.

[bluesuedesw]

FYI - I'm still seeing this crash with the LinkedIn cancel button on iOS 5 with the above changes.

[VilemKurz]

The fix is OK, I have just tested it. Please be aware, that it is not merged in master yet...