Removed ResultProvenance table & added DerivationEquations

* Removed ResultProvenance table, and clarified note regarding how a
combination of Action & MethodType could be used to perform this
functionality.
* Added DerivationEquations table, which adds additional functionality.
* Rather than add DerivationEquationID to the Results table, created a
cross-ref table with 1:1 (or 1:0) cardinality, similar to
ResultNormalizationValues.