Server configuration refactoring.

Factor out server configuration into a new flat file for easier setup of
new intallations and overall improved DRYness.

TODO: get cah.js to share in the common setup file without revealing the
admin password.
Replace Postgres dependency with YAML flat files

The Postgres dependency complicates development and deployment of the
application. Given that while running most of the data is kept in memory,
that there are a relatively small number of cards, and that the relational
features of the database aren't in use, we can instead rely on flat files
and native Python data structures.
Interpolate white card text in chat. Closes #3.

Instead of printing the black card text and white card text separately,
print the final winning text with white card text substituted for blanks
in the black card. This also cleans up the printing of blanks on the
client side.