Add magento-composer-installer dependency

Without this dependency the module won't by installable via composer.
Well, if another module happens to require it, it will work. But on
it's own it won't. :)
Merge pull request #12 from vinai-drive-by-commits/master

Add magento-composer-installer dependency
Merge branch 'release/1.0.0'
[~BUGFIX] Only sync orders which are not 'canceled', 'fraud', 'holded'
Version bump to 1.0.1
Merge branch 'hotfix/sync' into develop