Fix javascript, ffmpeg, php files

The job is about Rebuild Deleted Work: the person in chage of Git did not update the source to the last version and deleted ALL the files! and now final version is incomplete. This app creates videos from the browser by capturing the animation using javascript and then ffmpeg. All that works fine, but some parts needs to be rebuilded or DONE AGAIN. - Audios is not being added (it was working before), there are 2 sources of audio, user can choose 1,2 or none, ffmpeg need to be updated to add the audio to the video. (on button was changing some text to display that audio was being used, needs to be redone too - simple html) - When adding the audio get the audio duration so the small animation will last the same time of the audio duration (just get the time string and use it and add that duration to ffmpeg and the preview). - We optimised the rendering to avoid using cron jobs, so when asking for a slot to render it just check the available spots (usually 5) and then just render it, no need to wait for the cron job... that script is gone too, needs to be done again! - Short Tasks: I will send you an updated file with images to replace, some text to change, images folders should be sorted alphabetically, some text on a pop up needs to stay there, and need to move some buttons and resize a tab. - Bitbucket, need to create a new repo, needs to be updated with this changes.