Add missing maxctrl test cases

Code coverage revealed that some parts of the code could be easily
tested. Added these missing test cases and removed some dead code.

maxctrl/test/createdestroy.js

@@ -19,7 +19,7 @@ describe("Create/Destroy Commands", function() {
     })
 
     it('monitor without parameters fails due to missing user parameter', function() {
-        return verifyCommand('create monitor my-monitor mysqlmon', 'monitors/my-monitor')
+        return doCommand('create monitor my-monitor mysqlmon')
             .should.be.rejected
     })
 
@@ -273,5 +273,10 @@ describe("Create/Destroy Commands", function() {
             .should.be.fulfilled
     })
 
+    it('create filter with bad parameters', function() {
+        return doCommand('create filter test-filter qlafilter count 10')
+            .should.be.rejected
+    })
+
     after(stopMaxScale)
 });