Fix double reference of media recorder for blobs
Add mp4 stress test case for media recording
Add some mp4 media recording test cases
Add media element output for each mr
mediarecorder: It's blob.type, not blob.mimeType.

The fix unbreaks the test for me in Firefox 30.
Merge pull request #10 from rillian/mediarecorder

mediarecorder: It's blob.type, not blob.mimeType.