Target subversion plugin 1.50

Originally, this code was written as a patch to 1.51-SNAPSHOT.  Downgrading to latest release so it can be used in production, because no patch is likely to be accepted.
Merge pull request #1 from jenkinsci/master

Target subversion plugin 1.50
Downgrade to 1.45

The latest version of the subversion jar (not hpi) in the repo is 1.45,
so use that instead.
cleaning
Merge pull request #1 from paulkrause88/master

Downgrade to 1.45
Change ID to follow jenkins community conventions
clean up after skeleton generator

Help files
fix IllegalAccessError

The interface SubversionRepositoryStatus.JobProvider is inaccessable
(throws IllegalAccessError), so copy it locally.
Merge pull request #2 from jenkinsci/master

rename artifact
Merge pull request #2 from paulkrause88/master

fix IllegalAccessError and plugin help
Update README.md

Add (broken) links to build status and to wiki pages.
Simplify implementation based on https://github.com/jenkinsci/subversion-plugin/pull/43