INT-2855 File Tailing Inbound Channel Adapter

Two implementations:

  - native 'tail' command (e.g. tail -F -n 0 /foo/bar)
  - Apache commons-io Tailer

Further changes:

 - Add documentation to section "what's new"
 - Add a JUnit @Rule so the OSDFTMP test doesn't fail on Windows
Merge pull request #802 from garyrussell/INT-2855

* garyrussell-INT-2855:
  INT-2855 File Tailing Inbound Channel Adapter