Added bash scripts used for converting .cvc,.smt2 and .smt files
to llvm-lit tests.
Added top level target "check" that should be used to invoke all tests.
Right now it only invokes the llvm-lit driven tests.
When running llvm-lit driven tests allow extra parameters to be passed
to solver.

e.g.

$ llvm-lit --param=solver_params=--help .