Remove outdated to_unicode import from plugin utils (#916)
Remove outdated to_unicode import from plugin utils (#916)

The to_unicode method as fallback is no longer needed.
Ansible 2.2 deprecated to_unicode in favor of to_text. The to_text
method has been available since 2.2 and Trellis now requires 2.4+.
pressbooks/trellis,kalenjohnson/trellis,partounian/trellis,NicBeltramelli/trellis,proteusthemes/pt-ops,proteusthemes/pt-ops,kalenjohnson/trellis,roots/bedrock-ansible,buluma/trellis,cimocimocimo/cimo-wordpress-server,Twansparant/trellis-db-sync,Twansparant/trellis-db-sync,NicBeltramelli/trellis,roots/trellis,kalenjohnson/trellis,cimocimocimo/cimo-wordpress-server,proteusthemes/pt-ops,jeffstieler/bedrock-ansible,newtonne/trellis,newtonne/trellis,roots/trellis,partounian/trellis,jeffstieler/bedrock-ansible,jeffstieler/bedrock-ansible,cimocimocimo/cimo-wordpress-server,newtonne/trellis,buluma/trellis,cimocimocimo/cimo-wordpress-server,Twansparant/trellis-db-sync,NicBeltramelli/trellis,partounian/trellis,roots/bedrock-ansible,partounian/trellis,pressbooks/trellis,buluma/trellis,Twansparant/trellis-db-sync,buluma/trellis,kalenjohnson/trellis,NicBeltramelli/trellis