Bug 972573 - Add cancel button on the selection screen

Please review it. There are 2 main points to be modified.
 - not use "system value selector" to add cancel button.
 - add webcontacts/select as new for other apps when it wants to retrieve the actual value that user selected on selector screen and user need to select "email address" as well.
(refer to https://bugzilla.mozilla.org/show_bug.cgi?id=840515 for more detail)

Tested:
 - Unit test OK
 - Actual user operation on Emulator and keon device OK