Merge pull request #9 from josebarrueta/master

Issue #8 Add ability to resolve signing key based on Jws embedded values...
updated SigningKeyResolver concept to handle standard java.security.Key instances, and updated the SigningKeyResolverAdapter to include bytes convenience methods.
#8: Updating readme in preparation for a 0.4 release
#8: fixing Gradle block to be color coded
#8: more doc updates
#8: more doc updates
#8: more doc updates
[maven-release-plugin] prepare release 0.4
[maven-release-plugin] prepare for next development iteration