Fixed issue Unit Test requested Image from Internet

test_verify fails when there is no internet connection. Fixed this issue
by mocking the urlopen which downloaded the image from internet.Also included
a try except block to detect the error and raise exception when downloading the
image when no internet is detected.
Closes-bug: #1308466

Change-Id: I29095eed8a4ff05720567223f2cb1f834b1d8f26
Merge "Fixed issue Unit Test requested Image from Internet"