Updated cookie expires date parsing to meet HTTP spec

Checking for RFC822 or RFC850 formats in cookie-jar
Using clj-time via ring-core to generate dates in tests
Also fixed a typo in the 'expirable' URL that was giving a
false positive on the cookie expiry test
Don't strip out http-only cookies on https, http-only applies to javascript
Release 0.2.0
Bump version for development