Can't use $PORT in Procfile

[natevw]

I'm getting errors like this trying to use a Procfile that works with the main version:

dev_db: ./node_modules/multicouch/bin/multicouch --port $PORT local_data

yields:

Unresovled Substitution in dev_db: $PORT

The code currently only passes the "global" environment variables to the Procfile parsing helper and the latter does not calculate ports while parsing.

Haven't looked into its source, but I imagine the Ruby version must fill out the arguments later (while starting each instance) rather than sooner.

[rmg]

Resolved by 1389d37 via #27