Added support for Express >= 4.0.0

Added new Express 4 middleware dependencies.
Resolved ```route``` property rename to ```mountpath```.
Resolved ```req.params``` type change from Array to Object.
Updated example for compatibility with both Express 3.x and Express 4.x (though using dependencies that technically aren't required in Express 3.x - might be a better way.)
Updated ```single``` expression in ```router.get(reGet…)``` to allow override using single query param (so tests pass.)
Updated ```single``` expression in ```router.get(reGet…)``` to return correctly for URLs that are more than 2 deep (so tests pass.)
Changed regex test in findPath() to test whether ```idx``` is numeric, not ```o```.
Confirmed test suite completes successfully against Express 3.0.0rc4, 3.6.0 and 4.2.0.