Upgraded Courier assemblies.
`PersistenceManager.Default` was obsoleted, replaced calls with `ExecutionContext.DatabasePersistence`
Fixed issue with Courier serialization.

When Courier was deserializing, it was treating any nested Archetype as a `JObject`.
The newer serializer routines in Archetype core resolve the previous issue.
Merge pull request #216 from leekelleher/feature/courier-upgrade

Courier upgrade (UaaS)
Merge pull request #218 from leekelleher/feature/courier-upgrade

Bug fix with the Courier resolver
Bug fix with the Courier resolver
Courier: Turns out that creating a new instance of `PropertyItemProvider` was a hack.

Replaced with getting the item-provider from the existing collection.
Merge pull request #220 from leekelleher/feature/courier-upgrade

Courier: Fix for PropertyItemProvider reference
Expose serializer for those wanting to create Archetypes from code
Merge branch 'develop' of github.com:imulus/Archetype into develop