Update RevealCKEmojiFilter for html-pipeline 1.9

Should close #13.
Start working with html-pipeline 1.9. Fix #13.

Merge branch 'compat-with-html-pipeline-1.9'

* compat-with-html-pipeline-1.9:
  Update RevealCKEmojiFilter for html-pipeline 1.9
[typo] Version info in RelishApp README
v0.4.1. See CHANGELOG.md for details.