[changed] handler keys to be optional

gimme some of that sweet, sweet DOM diffing

closes #97
fix typo in docs about dymanic segments params
Merge pull request #232 from mlusetti/master

fix typo in docs about dymanic segments params
Merge pull request #229 from rackt/no-keys

[changed] handler keys to be optional
[changed] `<Link/>`s to take params property

- old behavior is maintained, but logs a
  deprecation warning

- instead of passing in properties to fill in
  the dynamic segments, we just take it from the
  params object

closes #217