Updated requirements for browsertests

Change-Id: I0424b28b3d4b08ad3d9d3c2da62ceddd81e1bd6d
Require parallel_tests gem for browsertests

This will allow us to run some of the selenium tests in parallel which
will decrease time of the testruns

Change-Id: I2f0dd05dfc2d8b62530813e37894c754703ae90b
Merge "Updated requirements for browsertests"
Merge "Require parallel_tests gem for browsertests"