Composer support

[Casey Lee]

Hi, Thanks for your work. Do you plan to add composer support with this library?

vagrant@homestead:~/commerce.dev$ composer require gentle/bitbucket-api
Using version ^0.8.2 for gentle/bitbucket-api
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - The requested package gentlero/bitbucket-api could not be found in any version, there may be a typo in the package name.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, reverting ./composer.json to its original content.

[Alexandru Guzinschi]

The vendor name on Packagist is gentle not gentlero.

The requested package gentlero/bitbucket-api could not be found in any version, there may be a typo in the package name.