Custom handler popups

Custom handler popups

[Issue#] N/A
[Feature] Custom handler register callbacks should show popup.
[Problem] N/A
[Cause] N/A
[Solution] Popups added.

[Verification] Run manual test custom_handlers.wgt
1. Click register provider, check if popup appears.
2. Click again, popup should not appear.
3. Run widget again check if popup doesn't appear.
Repeat steps for content handler.

Change-Id: I0117dcaf098e5d5f98b9ccb5570a66ff315d07a9