Add _wait_till_text_present_in_element method

* add selenium configuration group
* add implicit/explicit wait and set page timeout

Partially implements blueprint: selenium-integration-testing

Change-Id: If39a5dcbac45635ad9988edfdc1830aeabc663a4
Wrong success url for instance floatingip related actions

When the instances is paginated in multiple pages, the success
url for floatingip related actions best to be the current page.

Change-Id: I1e35f984e4aa50457d3c59f80ceb01f091324656
Closes-Bug: #1354970
Merge "Add _wait_till_text_present_in_element method"
Merge "Wrong success url for instance floatingip related actions"
Merge branch 'master' of https://github.com/openstack/horizon