Show offline state of the application

[mathebox]

Is your feature request related to a problem? Please describe.
It is not transparent to the user if the application has a connection to the Internet or not.

Describe the solution you'd like
Show a badge on the tab bar when the application is in offline mode.

Describe alternatives you've considered
Show a badge on a custom refresh control (pull to refresh).

Affected Component
XikoloTabBarController, (Custom RefreshControl)