Create config package

What we're after

We need to pass the following configuration to the service:

• Host (can be empty, still valid)
• Port (must not be empty; could have a default of 8080)
• Reading frequency Edit: hardcoding to hourly for now.
• Log level (INFO default?)

The following do not need to be read in separately because their clients read conventional environment variables:

• Postgres environment variables (PG*)
• Cloud Foundry environment variables

Security considerations

None in scope. Sensitive envvar storage will be handled in product#3310.

Notes for implementers

• I suggest a new internal/config package with a Config struct and New() Config function. You could update run to accept a getenv function and pass that to the config package to enable easy testing.

Related issues/sub-projects