remove default stepMs

This way if any query is sent without a step param we simply return an
error (as it is a required query param).

Fixes trickstercache#98

handlers.go

@@ -917,8 +917,8 @@ func alignStepBoundaries(start int64, end int64, stepMS int64, now int64) (int64
 	}
 
 	// Failsafe to 60s if something inexplicably happened to the step param
-	if stepMS == 0 {
-		stepMS = 60000
+	if stepMS <= 0 {
+		return 0, 0, fmt.Errorf("step must be > 0")
 	}
 
 	// Align start/end to step boundaries

handlers_test.go

@@ -502,20 +502,30 @@ func TestAlignStepBoundaries(t *testing.T) {
 			0, 0,
 			true,
 		},
-
 		// query with start and end after now
 		{
 			2000, 3000, 10, 1,
 			0, 0,
 			true,
 		},
-
 		// query with start and end after now, with start after end
 		{
 			3000, 2000, 10, 1,
 			0, 0,
 			true,
 		},
+		// query with no step
+		{
+			1, 100, 0, 1,
+			0, 0,
+			true,
+		},
+		// query with negative step
+		{
+			1, 100, -10, 1,
+			0, 0,
+			true,
+		},
 	}
 
 	for i, test := range tests {