Fixed a couple typos

Fixed a couple typos in the README.
Merge pull request #2 from dwfreed/patch-1

Fixed a couple typos
Merge pull request #1 from google/vonhollen-dev

Adding code that was mostly reviewed privately
Merge pull request #3 from google/vonhollen-dev

Added actual PAM module, updated docs, and made a few minor fixes
Fixed default policy path typo in README.md
Merged README.md from master branch