Support lazy evaluation for routes

[TerrenceLJones]

Instead of only using a glob or regexp, it be nice to also have the ability to do the following:

 route('/myURL//:lazy_param', function () {})

[TerrenceLJones]

@brian-mann I've opened this issue as per our conversation on Gitter. My understanding of what really needs to be implemented is somewhat lacking. If I missed something can you help me formulate a more in-depth description of this issue?

[andersthorbeck]

This seems to be a variant of the feature suggestion in #387

[jennifer-shehane]

Closing as duplicate of #387