Don't set a secret_key in the Dockerfile

Setting the key in the `Dockerfile` means everyone that pulls the
image from the public index gets the same key. This moves the key
generation to the `setup-configs.sh` script.
Document configuration options
Provide sample config
Document Apache config
Fix email_exception documentation
Document secret_key
Document that the secret key is generated automatically if left blank
Document the index_endpoint
Final doctweaks
Merge pull request #80 from bison/secret_key_generation

Don't set a secret_key in the Dockerfile
Line-wrap at 80
Merge pull request #81 from ByteInternet/document-config

Document configuration options and document Apache config