Added .DS_Store to .gitignore
Added videos created in test suite to .gitignore
Revert "Added videos created in test suite to .gitignore"

This reverts commit ee7b082718e440a6c7e5745c1dcae01e4e28fc75.
Renamed videos in assets folder to not use test as a prefix like the output files the tests creates in order to add these output files in the .gitignore
Added an autoOrient command that reads the metadata of the video, finds out if the video needs to be rotated. If yes, it rotates the video using '-vf' argument for ffmpeg and it resets the metadata for the video to have rotation = 0. The code was tested to work fine but the API needs to be improved so that it can be used with chaining like new Ffmpeg().autoOrient().saveToFile(...) instead of calling autoOrient with a callback as I'm doing now