AssertionError messages not parsed by IntelliJ

The current error messages as defined in the default templates are not is a form that IntelliJ parses for diffs:

```
Expecting someField of:

to be:

but was:

```

With a slight tweak IntelliJ does parse them and allows you to view the diff:

```
someField of expected: but was:
```

I believe Eclipse works the same way. Of course, this might be a bit less nice to read as plain text.

@joel-costigliola Is this something you have considered? Would you accept a pull request for this change?