Housekeeping: Generate output files on prepublish; remove them from git

[anko]

I am irritated by how much the generated files in lib/ bloat the git tree when I commit to this project. It's unnecessary to check in generated output files!

The prepublish hook takes care that the output files are built on npm publish or local npm install.

For prior art doing this type of thing with a LiveScript library, see—

• for a trivial example, whatxml (which just calls lsc on prepublish), or
• for a more interesting and similar case, eslisp (which calls make on prepare).

Both store only check in the source LiveScript, not the generated JS.

[anko]

Egch. :angry: Travis is failing to run lsc to build package.json from package.json.ls because of course lsc isn't installed at that point because there's no package.json to tell it to.

I think having a build metadata file (package.json.ls) that needs to be built first using one of the dependencies that it is specifying is ass-backwards and a horrible idea.

[anko]

Now of course Travis chokes on the same [email protected] issue that I described and fixed in #117.

Ready for merge, after #117, in my opinion.