* Adds `impl_json_metadata!` for generating all metadata of a runtime
* Adds `json_metadata` RPC call
* Adds simple test for the `json_metadata` RPC call
* Implements json metadata in the demo runtime
* Fix indent
* Adds missing copyright headers
* Dispatch json metadata renamings and improvements
* Replaces `format!` & `String` with `Vec<JSONMetadata`
* Implements `Encode` and `Decode` for JSONMetadata
* Make `impl_json_metadata!` compileable on `no_std`
* Adapt the client to decode the correct type for `json_metadata`
* Fixes compile error and warning
* Whitespace