Added .githooks dir and pre-commit hook...

that runs htm and unit tests.

Fixes #203.
> Does this execute from the root or from the directory you are in at the time?

It executes from project root directory.

> Additionally, use pushd and popd to get back to the original directory after running tests.

No need to do that. Git takes care of it. I just tested committing from project root and within a subdir. Both times the tests ran properly and I was not moved out of my cwd afterwards.