Xcode 5 iOS 7 Support
Cherry pick of 14407e1.

Author: Egor Leonenko <jagor@leonenko.info>
Date: 19 décembre 2013 23:36:16 UTC+1

Call avformat_network_init() for all
Update Project
Comment out a LumberJack logger specific function call.
Update Rakefile for iOS 7.1, arm64 and a better version of gas-preprocessor.
Update gas-preprocessor submodule to use the latest version.
Update Rakefile to install the gas-preprocessor if it not found.
Move the screenshots out of the way.
Hide the status bar.
Add a auto-launch debug test and some log.
Fix a trivial deprecation warning.
Fix the slider bar vertical position for iOS 7.
Add a way to dump the audio samples to the trace log.
Minor code clean in the audio manager.
Add CocoaPod to integrate NSLogger.
Use NSLogger, or NSLog as a fallback.
Changed the deployment target to iOS 7.
Fix a few warnings for that.
Move the FFmpeg libs into libs/FFmpeg/ to give room for other libs.
Give a logger callback to FFmpeg.
Add a flag to define if the audio manager must dump the audio data.
Send the trace log only to the console of the user who is building the project.
Update Pods.
Add some sample video files to the bundle. Those files are not checked in, as they are not mandatory for compilation.
Remove the tabbar in the example project.
Add Podfile.lock and remove *.lock from the ignore list.