[feature]add images model to manage uploaded photos
[feature]user can upload picture to our system

Note: later will add features like:
1. upload the processed pictures to S3
2. set styles to uploaded pictures
[chore]add public/ folder to gitignore
[feature]new structure of images and users
[feature]user can set profile cover
[chore]add cover to user's cover_images
[feature]albums can set cover_image
Merge pull request #4 from peterzd/images

Images