Update core/src/main/java/hudson/model/Run.java

Handling NTFS symlinks introduced via Util.resolveSymlink.
JENKINS-15587
Also probably culprit for JENKINS-13972
Update core/src/test/java/hudson/model/RunTest.java

Added testParseTimestampFromBuildDir to deal with JENKINS-15587.
Minor updates.

Code style convention related updates.
Massaging the fix.

- ID_FORMATTER is time zone sensitive, so comparing against # of
  milliseconds since the epoch won't be portable.

- resolveSymlink can return a relative path.
[FIXED JENKINS-15587]

The actual fix was in the pull request #675.