CBQE-0: rename healthcheckerTests in HealthcheckerTests

Change-Id: I70fa93dee96ce004147ce02a7a7c0becf564256d
Reviewed-on: http://review.couchbase.org/30259
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>