Create design document for dynamic resolving of RVD location based on configuration

[otsakir]

Create a design document describing how restcomm can resolve relative rcmlUrls to RVD applications. The document should address the following:

1. The scope where this resolving will be applied. The Application rcmlUrl property for sure. What about voice urls in IncomingPhoneNumber ? Or maybe a global approach ?
2. The algorithm used in order to treat as a URL to RVD. for example, check if it starts with '/restcomm-rvd/'
3. Core components introduced or affected. An RvdResolver component seems like a good idea and Downloader maybe affected.
4. Configuration specification. Are there any new options added ? Semantics ?