They have been relocated to the corresponding classes.

Login option is not shown if the user is already logged in, and logout
option is not shown if the user is not logged in.

I've also removed a debug line from ProviderDetailFragment, which
returned true when it returned false because of an exception.

Feature #3023 first solution.

I don't like to tell anything to the user when s/he wants to exit
pressing the back button. I assume s/he is saying: "Wanna go out!!"

I've implemented the behaviour written in UI Rev II.

If a user selects a new provider when coming back from Switch Provider,
the previous provider is forgotten and we assume s/he wants to change of
provider but he is not sure to which. That means that previous provider
configuration will be removed (that means there is no provider selected
and Dashboard will not be launched before a new provider is selected).

Once in the provider detail fragment, if the user presses the back
button, provider.json is removed from sharedpreferences (so that
Dashboard does not start as if the user had selected the canceled
provider) and ConfigurationWizard gets the focus.

Buttons from this fragment are shown if the key is present and contains
a "true" value, but if an exception occurs the button it's not showed.

They are commented, just in case we decide to include any of them before
releasing 0.2.0.

Tested with dev.bitmask.net, I use the previously downloaded certificate
(I should not do that, I'll file an issue because I should download it
once the user has requested to do so).

Next step: login button from ProviderDetailFragment.

Domain, name and description come from provider.json

Next step: code buttons to login or to use anonymously.