issue #360: Add support for committing multiple files

[siordache]

Implement #360. New classes:

• GHBlobBuilder - create a blob
• GHTreeBuilder - create a tree
• GHCommitBuilder - create a commit

This gist shows how to use the new classes.

[siordache]

@reviewbybees

[ghost]

This pull request originates from a CloudBees employee. At CloudBees, we require that all pull requests be reviewed by other CloudBees employees before we seek to have the change accepted. If you want to learn more about our process please see this explanation.

[jglick]

@siordache please do not use the above mention. @kohsuke is I think the only one who can now delete the previous two comments.

[siordache]

Oh, sorry. I thought that I should use the above mention to indicate that the PR is ready to be reviewed.

[KostyaSha]

This is not a jenkins, this @kohsuke owned library. Unfortunately jenkins plugins depends on it, maybe we should raise the question on forking it, because it causes delays for FOSS users. Only those who work with @kohsuke now can influence on releases speed.

[jglick]

Yes, various people have requested that @kohsuke move ownership of this and some other repositories necessary for Jenkins to the @jenkinsci org, or otherwise open up access.