Miscellaneous changes

Changes for this PR as proposed by @smcgregor :
1. rename extension to just "Privly"
2. move the tests directory into the javascripts directory
3. drop pages.css
4. clean up extra whitespace from files
5. cleanup the background.html file (it should not have "test cases" in it)

This whitespace is necessary. Two spaces at the end of a line in markdown produces a line break.