Implemented `Router#define`
DRY’ed Router#initialize
Clarified Router#define in the README
Removed README, based on Luca’s feedback [ci skip]
Added more method documentation [ci skip]
Merge pull request #17 from fredwu/define

Implemented `Router#define`
[ci skip] Define next version in doc as x.x.x
Prefer `if/else` over `unless/else`
Added missing test_helper require
Merge pull request #18 from fredwu/misc_tweaks

Misc tweaks