make all new customizations configurable

client/stylesheets/base.less

client/stylesheets/utils/_chatops.less

client/views/account/accountPreferences.coffee

client/views/account/accountPreferences.html

client/views/app/message.coffee

client/views/app/room.coffee

client/views/app/room.html

i18n/en.i18n.json

i18n/pt.i18n.json

packages/rocketchat-chatops/i18n/en.i18n.json

packages/rocketchat-chatops/server/settings.coffee

packages/rocketchat-lib/settings/server/startup.coffee

server/methods/saveUserPreferences.coffee