Secure File Sharing System (Berkeley CS161 proj2)

The client will be written in Golang and will allow users to take the following actions:

• Authenticate with a username and password;
• Save files to the server;
• Load saved files from the server;
• Overwrite saved files on the server;
• Append to saved files on the server;
• Share saved files with other users; and
• Revoke access to previously shared files.

Implementation is in client.go, and tests are in client_test.go.