Error handling and hints for common problems added. "perltidy_enabled" implemented.

* Exception handling for running perltidy added. Errors will be checked
  for some common errors and additional hints will be printed on the
  ST2 console.
* Restructured code and moved perltidy command validation to
  is_valid_perltidy_cmd().
* Logging moved to log().
* get_perltidy_rc_path() renamed to find_perltidyrc_in_project().
* Searching for perltidy is now done in 3 steps, with fall back to some
  platform specific defaults. This might help with standard Strawberry
  installations on Win32.
* Additional diagnostic messages added, when running with
  "perltidy_log_level" >= 2.
* Documentation updated.
* Version bumped to 0.1.0. Using kind of Semantic Versioning now.
  See http://semver.org/ for more info.
Fixed error: "NameError: global name 'pp' is not defined". Should have been self.pp() instead.
Fixed WindowsError 6 "Invalid handle" while running perltidy on Win32.

* WindowsError 6 "Invalid handle" occured, while running perltidy via
  subprocess and using temporary files for I/O with perltidy. The error
  occured, because we were not passing PIPEs for STDIN/STDOUT to
  subprocess. This seems to occur on Windows XP only and is somehow
  related to http://bugs.python.org/issue3905. Fixed by always
  providing subprocess.PIPE for all three handles.
Revert package_control.json
Added Changes to README
Update package control
Cygwin support added. Tests added. Settings now reloaded on each PerlTidy run.

* User setting "perltidy_options_take_precedence" added. If set to "true",
  which is the default, options from user setting "perltidy_options" will
  take precedence over options found in perltidyrc files.
* Added automatic detection of perltidy in default installations
  of Strawberry Perl/ActivePerl/Cygwin on Windows.
* Settings are now reloaded on each run of PerlTidy.
* Now using sublime.platform() instead of os.name for getting platform
  name.
* Now catching EnvironmentError exceptions instead of OSError in
  tidy_region(). This will also catch IOError exceptions, which previously
  were not catched at all.
* Added messages to be displayed by Package Control on installation
  and upgrades in "messages/". Added "messages.json" to link the messages.
* Removed accessors: get_perltidy_options(), get_perltidy_rc_paths().
* Refactored most of the code and moved it to perltidy/helpers.py, so we can
  test it, without mocking too much.
* Documentation improved.
Bumped plugin version number. Latest version does not appear in package list.
Documentation updated.