Added deselect functions to selenium fixtures

* Added deselect() function
* Added deselect_by_value() function
* Added deselect_by_text() function
Merge pull request #397 from psav/enhance_select

Added deselect functions to selenium fixtures
Made tabstrip react to other type of strip found in the Configure / My Settings
Merge pull request #398 from mfalesni/tabstrip_extension

Made tabstrip react to other type of strip found in the Configure / My Settings