Refactor - output files and logs

[vinicvaz]

• [x] Allow to save output videos as .mp4 instead of .avi https://github.com/EthoML/VAME/issues/31
• [x] Fix .mp4 codecs for browsers https://github.com/EthoML/VAME/issues/35
• [x] Fix codecs https://github.com/EthoML/VAME/issues/35
• [x] Save umap visualization as image file https://github.com/EthoML/VAME/issues/30
• [x] Fix umap_vis for cohort=False https://github.com/EthoML/VAME/issues/38
• [x] Saving as png output of vame.visualization()
• [x] Add logger class to be used in main pipeline Fix https://github.com/EthoML/VAME/issues/37

Allow to save execution logs as files in project folder.

• [x] egocentric_alignment
• [x] csv_to_numpy
• [x] create_trainset
• [x] train_model
• [x] evaluate_model
• [x] pose_segmentation
• [x] motif_videos
• [x] community
• [x] community_videos