Revert "Removed check for MPEG version and layer"

Also added check for mpeg layer 2.

This reverts commit 5e4c916ccff7f87916b4d247540639ab0328abbc.
Pass file size function directly to parsers

This is instead of adding the function to
the underlying stream object. Extending the
stream object seems to cause a weird bug in
node 0.8 with multiple tests reading from
the same file.
0.4.0
Actually pass filesize func to parser. Fixes #56
Fix travis url
Disable non file stream test for now

There's a weird race condition that causes
test-non-file-stream-duration.js to fail occasionally
when running the full test suite.
0.4.1
Don't emit data back to the stream passed to us. Fixes #59
Don't automatically close the internal stream
0.4.2
Calculate flac duration

Issue #57
Calculate asf duration

Fixes #57
0.4.3
Browser 0.4.3