CBLT-287: remove Android emul tmp dir before start

Change-Id: I5cc3096f4a670aaa3d027d324c6f96c1149aa016
Reviewed-on: http://review.couchbase.org/36839
Reviewed-by: Traun Leyden <tleyden@couchbase.com>
Tested-by: Traun Leyden <tleyden@couchbase.com>