Added component field and refactored static fields to global.jelly

[JeremyMarshall]

Hi

This is my first pull request so let me know if I've gone about it wrong

I wanted to integrate jUnit output ito Jira but I also wanted to attach the bugs to a component in a project.
This fails with an exception if the component doesn't exist (like it does if the project isn't valid) but will ignore a blank component

I also refactored the server and user to a global config page as this is the approach the Jira/Jenkins plugin takes.

I think it will fail the tests as it stands

Please let me know if there is anything I can do to package my change better

Regards
Jeremy

[chcg]

@JeremyMarshall Code changed in this area so the PR can't be applied anymore. Some aspects of the change seem to be already implemented by the changes since the PR was created. Are you still interested to resolve the conflict or could this PR be closed ?