MB-8972: implemented PhantomJS-based ui testing

[alk@tut.by: edited commit message]
Change-Id: Icc312bd7e760f6170589354b11410fa72f26e03a
Reviewed-on: http://review.couchbase.org/28948
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>