[CS] Build on more Ruby versions
[UPDATE] Bump minimum Celluloid and Nokogiri dependencies
[BUGFIX] Pass SSML documents through a serialisation step for safety
Revert "[BUGFIX] Pass SSML documents through a serialisation step for safety"

This reverts commit 925e0fcc767652318a8b40f0d719ba1c979a680c.
Merge branch 'refs/heads/develop' into feature/multi_ruby
[CS] Add rb-fsevent for easier test runs with Guard
Merge branch 'refs/heads/feature/multi_ruby' into develop

Conflicts:
	punchblock.gemspec