Fix hook error in browser reporter by moving body prop from test to runnable

[danielstjules]

Fixes Uncaught TypeError: Cannot read property 'replace' of undefined when an exception is thrown from a hook.

Example test suite that correctly renders after the PR:

before(function() {
  throw new Error('uh oh!');
});
it('test', function() {});

[andrei-picus-hs]

Why hasn't this been published to npm?!

[screendriver]

+1 for a release because I can't use Test'ems CI feature. My CI builds are hanging forever because the browser will not be closed when mocha isn't failing correctly 😭

[stevebartholomew]

Presume this is a regression as the same issue was fixed a while ago: #270 - +1 for release :)