Add ability to suppress display of crumbs

[alerque]

In my research for this issue on Busted, the direct cause of the output is the decisions by this library to always output crumbs if they exist. For example in my specific case with the table formatter, this bit of code only considers whether the function exists (hard coded directly above) and whether crumbs exist. If they do, it outputs them.

There should be some way to run assert statements such as assert.same() with an extra argument or after setting some configuration value to suppress the output of crumbs and just get the pass/fail status in return.

Note that referenced code almost certainly isn't the place to fix this, somewhere upstream those formatters are getting called and they should be disabled at the source to suppress even the "Actual/Expected" strings.