Adding support for PORT env var

[drusellers]

Here is a simple commit for adding support for a PORT env

I have also added a sample Foreman for running things as well.

The ENV VAR overrides any current configuration.

I tested this code with

• foreman start - the app boots with port 5000
• ENV=4900 lein run - the app boots with port 4900

[qiuxiafei]

merged!