composer.json not loading the module because of zendframework version requirement

[adragos]

this

"require": {
    "php": ">=5.3.3",
    "zendframework/zendframework": "2.0.0beta4",
    "facebook/php-sdk": "v3.2.1"
},

should be updated to

"require": {
    "php": ">=5.3.3",
    "zendframework/zendframework": "dev-master",
    "facebook/php-sdk": "v3.2.1"
},

otherwise, anyone using a newer version of ZendFramework 2 will not be able to install this module using composer.

[widmogrod]

Pull request please.