Added a patch-add command. Fixes issue #3.
Merged in command-add-patch (pull request #2)

Added a patch-add command. Fixes issue #3.
Added 'why' section to README
README.md edited online with Bitbucket
Change patching message from 'ok' to 'success'
Copy the _drush_is_url() function to add compatability with Drush 5.x.
Cleanup errors and messages.
Add support for --force in the patch-add command which if the patch failed to apply, still add the patch to the patchfile.
patchfile_drush_pm_post_download() should manually pass in the project directory to fix apply patches to modules that do not use the standard module directories (like ubercart).
Fixed error if drush_get_context('DRUSH_DRUPAL_ROOT') is empty.
Colorized patch status.
Issue #1: Added composer.json.
Use drush_shell_cd_and_exec() when running patch commands.
Fixed error when using an alias that doesn't match the same local directory.
Run patch --dry-run before attempting to apply a patch to prevent reject files.
Issue #15: Adds a new patch-apply-all command.
Issue #17: Added support for downloading patch files from Drupal.org issues (with optional comment).
Issue #11: Prompt user to add new patch to patch file when it fails to apply.