Added getEnv and getRawEnv methods

Two methods were added to add the ability to access the environment variables from an existing Yamlenv instance. Without needing to use the existing env/getenv functions.

The getEnv method works the same way the env() and getenv() functions work. The advantage here is the ability to load the Yamlenv as a singleton in your framework, then reusing that singleton in your classes to access the env values. Thus removing the hidden dependency that the env helper functions ( like the one laravel uses ) in your own classes.

The getRawEnv method gives us the ability to load raw values like associative arrays from the Yaml file directly. Thus giving you the full power of the Yaml method instead of just the flattened env variables.