ticket:2. Important improvements explained below;

- by pressing Back button while getting user info you can actually interrupt the task, not just hide it;
- getting user task survives activity recreation (screen rotation, etc);
- dialogs survive activity recreation;
- if getting user task failed go back and check connection;
- workflow progress survives activity recreation: after screen rotation we skip work that already done and go directly to the current state (connection checking, facebook login, user retrieving);

Non-important:
- set UI string to be non-translatable;
- log application key on startup;