Remove Selenium test suite

Removing selenium test suite after a discussion on [1] and holding a
moratorium (one month period) for a possible intervention.

[1] http://wikimedia.7.x6.nabble.com/SMW-Selenium-tt5013521.html#none

Change-Id: Ib674ad16fb2386a0fe5c6bae0c0aeb7c1a20271b
Merge "Remove Selenium test suite"