Improve error reporting

In case of errors, the selenuim testcase extracts the test
name, error message and source of the error from the qunit
page and logs them, so that it's easier to locate the issue.

Also added 'from __future__ import absolute_import' to avoid
issues with importing the selenium library from the script
named selenium.py

Change-Id: I040d147ad9c78fe48080b6a01ff1b4d89d6e9c3e
Merge "Improve error reporting"