Update createClient method to better adhere to docs

See: https://github.com/mranney/node_redis#rediscreateclient
Fix Redis defs to better describe API.

- Merge all callback interfaces into a generic interface.
- Add CommandT generic interface for future use, to not have to
explicitly define all command signatures. At the moment a duplicate
definition is thrown is used, as commands like ```get``` have additional
signatures defined.
- Add rest parameter array to all commands, as all command accept either
an array or paramarray (see:
https://github.com/mranney/node_redis#sending-commands)
- Update tests to test that paramarray is working as expected.
- TODO: Add CAPITALISED versions of commands.
- Add myself to header info.
Merge pull request #2900 from CodeAnimal/redis

Update Redis definitions to have generic types and Rest ParamArrays.