Revert "Fix for Stanford's new interstitial login page."

Apparently Stanford decided to remove the interstitial page, so this is no longer necessary.

This reverts commit e39c8cbed1c5b9b57bf3f16bf227d2d912627cf1.
Merge pull request #3 from elliottslaughter/master

Revert skipping interstitial page
Changed BeautifulSoup import to work with bs4 on Ubuntu
Changed download code to skip a video if the .mp4 OR .wmv exists already
Changed login code to handle either the presence or absence of
the interstitial page (it doesn't show up for me)
Added easy-install commands and fixed a link title in the Readme
Minor edits to README