- Change the default Docker port to 2375 to match current Docker version.

- Add toString() to all commands which prints out a form similar to the
  corresponding Docker command line.  Useful in tracing.

- Create client logging filter variant which allows us to avoid logging
  requests whose content type is likely to cause issues for both the
  Windows and OSX consoles.  This is an adaptation of a change from a
  while back
  (alexec@887a112)
  which seems to have be lost in the move.

Revert API version which was by accident

Fix bug in logging filter

Add extra check to test to avoid downstream issues

This uses the recommended strategy to normalize line endings for mixed
Windows/*nix development.  We also make sure that the shell scripts used
for testing have Unix line endings on all platforms so they will function
properly.