Settings page ChangePassword page and their tests

Two new pages added: Settings page and ChangePassword page.
To test their functionality I wrote two tests:
1. test_user_settings_change
 * changes the system's language
 * changes the timezone
 * changes the number of items per page (page size)
2. test_password_change:
   changes the password, verifies it was indeed changed and
   resets to default password.

To allow the above I've made few changes in other places:
* projectpage - added the go_to_settings_page method.
* helpers - added Selenium's implicit wait for self.driver
  in order to use page_timeout for pages that don't load
  instantly.

https://wiki.openstack.org/wiki/Horizon/Testing/UI

Partially implements blueprint: selenium-integration-testing

Change-Id: I24e01cd13d4a63ffd82505e4fd9cc95ba887e882
Merge "Settings page ChangePassword page and their tests"