Captive portal handling

We now notify the user of a captive portal before switching to the network as default.
This allows background applications to continue to work until the user confirms he
wants to sign in to the captive portal.

Also, moved out captive portal handling out of wifi as a seperate component.

Change-Id: I7c7507481967e33a1afad0b4961688bd192f0d31
18 files changed