online_mp4_duration v2.0.8

#Online_mp4_duration
This module can get online .mp4 file's duration
##Usage
npm install online_mp4_duration
var onlinemp4duration = require('online_mp4_duration');
onlinemp4duration({url: 'http://example.com/instance.mp4', full_scan: true/false}, function(err, duration){})
full_scan enables you to decide whether it will scan through whole mp3 file if there's no metadata in the first 1MB and the last 1MB
##Notice
1) this module won't check the url, you need to check user input yourself.
2) I can't have good test .mp4 url, so there may be lots of bugs. Feel free to send PullRequest :D