Add sclj executable

The command `sclj` will be provided via the NPM module. People can later
install the module on there system and execute Clojure scripts or a REPL
via this command.
Add TODO files to Git ignore

Personal TODO files should not be committed.
Add command line handling to sclj command

The `sclj` command can be launched with a script to evaluate or a file
containing a script. It can also be launched with both. This is similar
to the behavior of the Clojure command line interface.
Add unit test infrastructure

Unit tests will be done with Mocha and Chai for assertions. The
automation is done by Grunt. There are currently no tests and no code to
test, but this should change soon.