Added site smoke test for API and Manual

Set up geb pages for the homepage, manual table of contents, and the api index page.
Merge branch 'geb' of git://github.com/beckje01/ratpack
#152 define PathTokens type
type coercion methods on PathTokens

Fixes #152
#152 Fix codenarc violations
#152 convert PathTokens to an interface
Remove the asset serving to only ever do one blocking read for file metadata.
Don't send a full http response if we are sending a file.
Upgrade to Netty 4.0.7.
Fix test to only send one accept header value.
Reworked some of the text on the front page (closes #51)
remove redundant comment
Close the channel if there's a problem serving the file.
Fix groovy link on front page.
Run browser tests on saucelabs for ratpack-site
Merge branch 'master' of github.com:ratpack/ratpack