minor bug fix

ZBFGS was not updating the natural occupation numbers properly.
Test suite required a small change for consistency
removing unnecessary shared pointers in zcas member functions
more shared pointer removal for zcas
Revert "more shared pointer removal for zcas"

This reverts commit 32473cdbdf7bad51989285aa09dd95b896c65138.
Revert "removing unnecessary shared pointers in zcas member functions"

This reverts commit 24a4382565bd272da085212b81bc7fe5b8adf16a.