[WIP]: Update Reflection component to v2

Part of the operation for speeding phpDocumentor up is removing the extra step of putting the parsed contents in Descriptors using Reflection objects. Instead Descriptors will be assembled directly from the parsed contents.

In this PR I have removed all descriptors as they have been moved to the Reflection Component and changed all files to match the updated API for the Descriptors.

In addition to this the minimum PHP version is updated to 5.4 to match the new Reflection component
`$this` is an instance of `phpDocumentor\Application` which extends `Cilex\Application` which extends `Pimple\Container` in return. The Container of pimple is an object containing the actual parameters and services of the whole application and functions as Dependency Injection container.

To retrieve a service or parameter you can approach the container (and any derived class) as it were an array (due to the ArrayAccess interface implementation as @boenrobot mentioned)