Log Message:
Update py-click to 6.2.

Add test target.

Version 6.2
-----------

(bugfix release, released on November 27th 2015)

- Correct fix for hidden progress bars.

Version 6.1
-----------

(bugfix release, released on November 27th 2015)

- Resolved an issue with invisible progress bars no longer rendering.
- Disable chain commands with subcommands as they were inherently broken.
- Fix `MissingParameter` not working without parameters passed.

Version 6.0
-----------

(codename "pow pow", released on November 24th 2015)

- Optimized the progressbar rendering to not render when it did not
  actually change.
- Explicitly disallow nargs=-1 with a set default.
- The context is now closed before it's popped from the stack.
- Added support for short aliases for the false flag on toggles.
- Click will now attempt to aid you with debugging locale errors
  better by listing with the help of the OS what locales are
  available.
- Click used to return byte strings on Python 2 in some unit-testing
  situations.  This has been fixed to correctly return unicode strings
  now.
- For Windows users on Python 2, Click will now handle Unicode more
  correctly handle Unicode coming in from the system.  This also has
  the disappointing side effect that filenames will now be always
  unicode by default in the `Path` type which means that this can
  introduce small bugs for code not aware of this.
- Added a `type` parameter to `Path` to force a specific string type
  on the value.
- For users running Python on Windows the `echo`) and `prompt` functions
  now work with full unicode functionality in the Python windows console
  by emulating an output stream.  This also applies to getting the
  virtual output and input streams via `click.get_text_stream(...)`.
- Unittests now always force a certain virtual terminal width.
- Added support for allowing dashes to indicate standard streams to the
  `Path` type.
- Multi commands in chain mode no longer propagate arguments left over
  from parsing to the callbacks.  It's also now disallowed through an
  exception when optional arguments are attached to multi commands if chain
  mode is enabled.
- Relaxed restriction that disallowed chained commands to have other
  chained commands as child commands.
- Arguments with positive nargs can now have defaults implemented.
  Previously this configuration would often result in slightly unexpected
  values be returned.