add etherpad-lite dependency to chocolatey.config

also add some clarification to the docs about what chocolatey does
and doesn't do
#527 - Returning group profile on updates
Fixed up collaborative document.
Setting etherpad's default pad text to empty for a travis run.
Single quotes need to be doubled in Travis YAML files.
Reverting sed fix and postponing till later.
Merge pull request #525 from stuartf/chocolatey

add etherpad-lite dependency to chocolatey.config