Clarify placement of 'where'

For server routes, see issue #88.
Update README.md
Merge pull request #301 from ariemer/patch-1

Clarify placement of 'where'
Added failing test case for simple optional paths.
Fixed #328
Basic test for integer params. For #330
Added option to customise the IronRouter/IronLocation anchor selector IronRouter.configure({"anchorSelector":"a[href][data-custom='true']"