Feature/algebra

Okay, main changes:

Tests for CSCMatrix Operators under OptimizationSpace
FrobeniusMatrixNorm is better
Minor refactor to CSCMatrixOps 

Probably the former. It's is cleaner, though the latter is more efficient. (Possibly you'll want to use the keysAlreadyUnique/keysAlreadySorted feature to save the sort in the result method.)