Update build

I haven't touched this project is a little bit of time, so I bumped a
lot of versions and cleaned up the build.sbt a little.
Convert timing to Google Caliper project

I'd hand-rolled my own benchmarking "framework".  It wasn't a horrible
attempt, but I think the Caliper project seems a bit more thoughtful and
polished.  I'd probably use it in a professional project.
Cosmetic change to build.sbt

Just moved a line up.
Providing SBT launcher in project

This makes the project a little more accessible.  Normally I don't like
checking in binaries into Git repositories, but I think this one won't
hurt.

I also adjusted the README.md file accordingly.
Add to .gitignore
Refactor polymorhphism packing

The file containing PolymorphismSpec was really defining the
polymorphism package more than defining the specification, so I renamed
the file to polymorphism.scala and moved it accordingly.
Comment out XLint option

I think this option might be more experimental.
Whitespace only change for readability
Rename curryhoward package name

I decided that underscores are fine in package names for this project.
Prime stream to study stream memoization