Sometimes it is not possible to reproduce failure in integration test
locally. Adding html source code of page where failure happened should
increase our ability to debug properly errors on the gates. For this
purpose the addDetail method from testtools package is used.
Following changes were done:
* TestCase and AdminTestCase classes were modified in order to share
common functionality and remove code repetition.
* Testcases have been modified in order to use newly introduce class
variables(TEST_USER_NAME, TEST_PASSWORD, CONFIG).
* Methods _get_page_html_source and _dump_page_html_source have been created
in the BaseTestCase class. _get_page_html_source uses javascript innerHTML
attribute in order to make javascript modification to the page visible
in the output. (javascript modificaton would not have been visible if
webdriver's property page_source was used)
Partially implements blueprint: selenium-integration-testing
Change-Id: I064405337fb68c966da007f2a5bf91d5c0ec2b3d
e74296fb20