Remove test file before starting test routine
Remove test file before starting test routine

* If previous test failed, the test file still exists in there and may
affect right next test which uses the same test file name. We should
remove it during initialization of each test.

Change-Id: I75053733a54c46eb4fe120671c1b866c11566ec2
Reviewed-on: http://review.couchbase.org/77731
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

couchbaselabs/couchstore,couchbaselabs/couchstore,couchbaselabs/couchstore