Allow non-text changes to plugins

Implemented by:

- disabling the check for msg.text == nil
- setting the match text to [msg.media.type]
Merge remote-tracking branch 'upstream/master' into nontext

* upstream/master:
  When text exceds 4096 chars, sends in multiple msgs
  resolves #18
  Update README.md
Merge pull request #19 from mrvdb/nontext

Allow non-text input to plugins