Basic implementation of jwt support, jasmine spec need some debugging
spec: fix jasmine test related to signature
doc: update documentation to reflect switch to JWT
fix: remove fancy ruby 2.X syntax to preserve 1.9 support
Retry one time messages that are rejected by the server in order to prevent message lost when signature expires or key change
Update README.md to reflect change in JS Extension

The constructor now takes the client instance as the first argument, needed for retrying.
Create CHANGELOG.md
Merge branch 'feature-jwt'

Conflicts:
	README.md