remove special error handler from addons

these are here for historical reasons; the generic handlers under
Heroku::Command.prepare_run are going to do a much better job now.

more specifically this will make sure addons commands are going to
follow generic auth rules like requesting for 2fa
Merge pull request #1296 from heroku/pedro-remove-addon-error-handler

Remove special error handler from addons
Fixed typos
Merge pull request #1299 from pborreli/typos

Fixed typos
started hk command
updates
renamed to jsplugins
able to run jsplugin commands
small refactor
added install command
added jsplugins:version
ensure jsplugin is setup
send args