BEL/RDF for MAPK pathway from large corpus
Add initial conditions to the model
Fixed a few bugs in rdf_to_pysb

- Prepending rules with underscores makes Kappa choke, so changed
  to 'p'
- The default parameters weren't getting added to the PySB model
Binding and activation of kinases

- Alternative rule structure specifies binding of kinases to substrates
- New query looks for rules of type pmod => activity state