service provider toFSOps defined
bug fix: accumulator's initial value should be empty
Shell semantics for services; ancestors method reused in place of parentdirs
OptExprModel evaluation code

- evaluation for create, delete, filter, shell and predicate
- isSatisfiable method added in Z3Puppet for checking satisfiability of single FSKAT expression
Test to check if FSKAT expression generated is satisfiable

- only tractable(2) tests enabled for now
- one is coming satisfiable but one is not
Merge branch 'master' of github.com:nimishgupta/rehearsal