Added mass_collatz.sh to run and diff all the tests

See source for invocation
Merge branch 'master' of github.com:cs371p-fall-2013/cs371p-collatz-tests
Merge branch 'master' of github.com:cs371p-fall-2013/cs371p-collatz-tests
Merge branch 'master' of github.com:cs371p-fall-2013/cs371p-collatz-tests
Merge branch 'master' of github.com:cs371p-fall-2013/cs371p-collatz-tests