Created a dynamic generic post with s3 storage and boto library:

- Added a Generic Post model
- Added created a Category model
- The AWS credentials are environment variables
- The posts and the categories can be added via django admin panel
- The images are stored in s3 storage
- Enhanced the press template to support 'press' and 'blogpost' categories
- Added a tag model to enable posts with multiple tags
- Added an image model to enable posts with multiple images
- Changed the s3 format from SUBDOMAIN to PATH