CBQE-0: add process check for couchbase uninstall(windows)

Change-Id: I093dce4d345139a3e6544ada5d8eecc7f174f2db
Reviewed-on: http://review.couchbase.org/30760
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>