Add latest version details, new contributor and make contributors more visible.
Treat undefined and null parameters as blank in signatures.
Remove content-length for GET requests.

Partial revert of 693f893. Content-Length was required because
the data was accidentally being sent in the body of GET requests.
This should only be done on POST.
Bump version number -> 0.8.3
Merge branch 'hotfix/v0.8.3'