tests fail intermittently

[neilberkman]

Currently tests fail intermittently, depending on the seed.

3:42:22-neil~/act/furlex (master)$ mix test 
.............
Finished in 0.5 seconds
2 doctests, 12 tests, 0 failures

Randomized with seed 432148
13:42:25-neil~/act/furlex (master)$ mix test 
..............

Finished in 0.5 seconds
2 doctests, 12 tests, 0 failures

Randomized with seed 52231
13:42:27-neil~/act/furlex (master)$ mix test 
.....

  1) test unfurls a url (FurlexTest)
     test/furlex_test.exs:23
     Assertion with == failed
     code:  assert furlex.facebook()["og"]["site_name"] == "Vimeo"
     left:  nil
     right: "Vimeo"
     stacktrace:
       test/furlex_test.exs:29: (test)

......

  2) test parses Twitter Cards (Furlex.Parser.TwitterTest)
     test/furlex/parser/twitter_test.exs:8
     Assertion with == failed
     code:  assert {:ok, %{"twitter" => %{"image" => "www.example.com"}}} == Twitter.parse(html)
     left:  {:ok, %{"twitter" => %{"image" => "www.example.com"}}}
     right: {:ok, %{"twitter:image" => "www.example.com"}}
     stacktrace:
       test/furlex/parser/twitter_test.exs:12: (test)

  3) test parses Facebook Open Graph (Furlex.Parser.FacebookTest)
     test/furlex/parser/facebook_test.exs:8
     Assertion with == failed
     code:  assert {:ok, %{"og" => %{"url" => "www.example.com"}}} == Facebook.parse(html)
     left:  {:ok, %{"og" => %{"url" => "www.example.com"}}}
     right: {:ok, %{"og:url" => "www.example.com"}}
     stacktrace:
       test/furlex/parser/facebook_test.exs:12: (test)

Finished in 0.5 seconds
2 doctests, 12 tests, 3 failures

Randomized with seed 962996