[tools] Add payswarm all-in-one tool.
[tools] Add common tool utilities.

- Use shared configured jsonld.
- Tool creation function.
- Common command options.
- Config reader.
- Request wrapper to use common options.
- Common output and error functions.
[tools] Remove unneeded shebang.
[tools] Add URL tool.

This developer tool performs raw PaySwarm Authority URL access using
HTTP Signature authorization with key information taken from a
configuration file.

- Intended as a developer tool.
- Depends on jsonld.js with a dependency on node request module with
  HTTP Signature support.
- Can use arbitrary HTTP method via -X.
- Can send string, file, or stdin data.
- Basic check to avoid making signed cross authority requests.