fix message for assertEquals

The signature of assertEquals method is:

```ceylon
shared void assertEquals(
    "The actual value to be checked."
    Anything actual,
    "The expected value."
    Anything expected,
....
```

so, for this code:

```ceylon
test shared void run() {
    
    value actual = 1;
    value expected = 2;
    
    assertEquals(actual, expected);
}
```

i Would expect the message something like:
```assertion failed: expected <2> but was <1>``` instead i think the message is wrong saying: ``````assertion failed: expected <1> but was <2>``` 

I believe it was just a mistake using the arguments is wrong order...