Added value 'unknown' for 'Repository depth option'
Added a test case for verifying that depth 'unknown' works
[JENKINS-17974] Changed 'undefined' to 'as-it-is' in web interface of subversion-plugin
[JENKINS-17974] Move 'as-it-is' option to the end.
[JENKINS-17974] Updated help page so it refers to 'as-it-is' instead uf 'unknown'
Merge pull request #46 from ezjenkins/master

[FIXED JENKINS-17974] new SVN plugin option to leave --depth parameters as they are