Parse "bare" cookies in non-strict mode

[stash]

Some cookies with an empty value can look like name instead of name=. These should be parse-able in non-strict mode and round-tip when serializing to strings.

[stash]

Triage: should investigate if this is still an issue, sync up with the whatwg reference linked above?

[stash]

Related to this: check out http://inikulin.github.io/cookie-compat/ !

[ruoho]

Correctly parsing cookies with empty / no key was merged in #49. Let's create a new issue if we want to investigate the whatwg reference.