Implement a z3 runner.

Add a CheckerRunner class with a single static method to run z3.  It uses
the smtlib generators, and the logic can be extended to other smtlib2 compliant
smt solvers.  It uses the copy of z3 in your path for now.

Note that it is very brittle, and if z3 has issue can potentially lock the
thread it is running on, as Java has no easy way to add timeouts to reads
on the stdout of z3.

git-svn-id: https://groke.mcmaster.ca/svn/grad/colin/branches/TableTool_javization@10663 57e6efec-57d4-0310-aeb1-a6c144bb1a8b