Move asset compilation features more to Pipe

[CHH]

• Decouple the asset compilation from Bob
• Add a class for generation of Manifest files
• Add an Environment, which acts as a proxy to a Manifest file.
• Dump all assets registered in the Manifest with one method call.

[CHH]

AssetDumper and Manifest classes were implemented in 27a873821677b53aeeade6cf3de824518f3d3f70