Add support for proxy
Fixed issue with Jenkins CLI public key authentication
fixed formatting
A flag to allow authenticated users to create new jobs

Configuration setting for admins to enable/disable "Allow Authenticated to CREATE new jobs"

When enabled authenticated users can CREATE new jobs & then configure jobs to setup the repository so
regular repository level authorization takes effect.
Call fireAuthenticated if we can.

See pull request #26 for the context
Restoring backward compatible constructor
Merge pull request #21
Merge pull request #19

Conflicts:
	src/main/java/org/jenkinsci/plugins/GithubSecurityRealm.java
Unneeeded check as githubWebUri is guaranteed non-null at this point.

Personally, I'm fine with having a defensive check like this, but @skottler didn't seem to like this in a review comment in https://github.com/jenkinsci/github-oauth-plugin/pull/15/files so I'm respecting his opinion by removing this check.
Merge pull request #15

Conflicts:
	src/main/java/org/jenkinsci/plugins/GithubSecurityRealm.java
Use Jenkins' proxy configuration
[maven-release-plugin] prepare release github-oauth-0.19
[maven-release-plugin] prepare for next development iteration