Add mdfp entry for msnbc.com, newsvine.com

[eenblam]

Fixes #1293. Follows up on and closes #1570.

[eenblam]

EDIT: Closing and reopening to rerun build.

Firefox beta build is failing due to the following Selenium test timing out:

def test_should_not_detect_ls_of_third_party_script(self):
    # a third-party script included by the top page (not a 3rd party frame)
    self.load_url("https://rawgit.com/gunesacar/b366e3b03231dbee9709fe0a614faf10/raw/48e02456aa257e272092b398772a712391cf8b11/localstorage_from_third_party_script.html", wait_on_site=5)
    self.assertFalse(self.detected_tracking_by("githack.com"))

This seems to be an issue caused by either:

1. the network/Travis. Can we retry the build?
2. SuperCookieTest.detected_tracking_by checking the snitch map. I'm not sure how the requested change would create such a drastic hit to performance, but I'm looking into it presently.

[cowlicks]

I think this is indented with a tab, can you replace it with 2 spaces?

[eenblam]

Yeah, my bad. Accidentally had shiftwidth and tabstop set in Vim without expandtab, so it looked right on my end despite the difference.

[cowlicks]

Thanks @eenblam !