tor: use string comparison to check min supported version

The current method would not allow version strings like 0.4.0.5 since it
would check every number of the version string individually.

tor/controller_test.go

@@ -28,6 +28,10 @@ func TestParseTorVersion(t *testing.T) {
 			version: "0.4.3.6",
 			valid:   true,
 		},
+		{
+			version: "0.4.0.5",
+			valid:   true,
+		},
 		{
 			version: "1.3.3.6",
 			valid:   true,
@@ -56,6 +60,10 @@ func TestParseTorVersion(t *testing.T) {
 			version: "0.1.3.6",
 			valid:   false,
 		},
+		{
+			version: "0.0.6.3",
+			valid:   false,
+		},
 	}
 
 	for i, test := range tests {