Migrate to s3

[Shubhaankar-Sharma]

What we want to do is strip down the whole CDN, and make it for uploading files only, to an s3 bucket.
After Uploading we should store the s3 asset URL in the assets table, we have to remove the files table as it would be useless now.
Tasks:

• Remove Get Asset Endpoints
• Use s3 SDK to upload files instead of database
• Clean up files remove models, tables, write a migration to delete table
• Migration to add an asset URL field
• Complete List assets and other endpoints.