Moves checkout step calculation to client instead of each sub-view
Simplifies code for displaying the error lists
Simplifies code for displaying error list
Simplifies code in catalog list header
Adds meta tags for list and detail view
Adds i18n object to context
Merge https://github.com/Arcavias/arcavias-core

This re-merges commit b94bab3fc834d8536db5fa6233f9bd8e7e86bea8.