Add RavenHQ connection string to Web.config.

In the checked-in file, use an Embedded instance of RavenDB for local
development. The connection string must be added to Web.config for Azure
to override it at runtime. This means the [Debug|Release]RavenModule
classes can be collapsed down to a single class, which is a nice
side-effect.
Merge branch 'feature/raven-connection-string' into develop