fixed the name conflict error
using a managed property in the Namespaces spec
Adding terminology for InputDataset, OutputDataset and Shadow concepts
Adding Dataset definitions
Shadow workflow
Adding general Shadow term
Updating terms
Merge pull request #248 from ambiata/topic/shadow-terminology

Shadow terminology
Merge pull request #250 from ambiata/topic/using-managed-properties

Using managed properties
Spelling in extraction scaladoc
Lift frequency option from virtualDefGen
Cleanup imports for Snapshot
Added ArbitrariesDictionary and VirtualDictionary
Use VirtualDictionary arbitrary in DictionaryImportValidateSpec
Add mandatory expression to virtual definition
Merge pull request #254 from ambiata/topic/dictionary-expression

Added expression to virtual definition
Remove unused imports
Introduce SnapshotWritable for sorting by time/priority and remove PriorityTag
Add hashCode for SnapshotWritable
Use repo.snapshot in PrintFactsSpec