Expand examples on using the bypass_scf option.

1. Doing a triplet detci calculation after a singlet scf calcution
   requires a ROHF reference and an explicit call to generate the MO
   integrals.
2. Add an example for doing an FCI calculation after a CISD one, which
   requires the SO two-electron integrals to be kept.

(The rasci-ne test also includes calls to
psi4.IOManager.shared_object().set_specific_retention, but these don't
appear to be necessary in these examples, for reasons I can't figure
out.)
Merge pull request #25 from jsspencer/doc_bypass_scf

Expand examples on using the bypass_scf option.