Fix #7 support for dev=1 and version=... in query string

1) Code changes to support `dev=1` / `dev=true` and `version=...`
2) Removed AT 1.3.5 from this repo.

Prerequisite to have things working is to fork https://github.com/jakub-g/atcdn/commits/gh-pages to `atcdn` repo on your side first (IMO it's better to have stuff separated).

Quick tests:

http://jakub-g.github.io/instantat/?dev=0&version=1.3.7
http://jakub-g.github.io/instantat/?dev=1&version=1.3.7
http://jakub-g.github.io/instantat/?dev=0&version=1.4.4
http://jakub-g.github.io/instantat/?dev=1&version=1.4.4

(defaults: dev=0, version = 1.4.4)