New command: chel serve

[taoeffect]

Problem

We need the ability to serve Chelonia apps.

As a preliminary first step, something simple is needed.

Solution

Implement a chel serve command that looks something like this:

chel serve [options] <directory>

OPTIONS

-p,--port <port>        set port (default: 8000)
--db-type <type>     one of: files, sqlite, mem (default: mem)
--db-location <loc>  for "files", a directory, for "sqlite", path to sqlite database

Note: will need to create @chelonia/lib to do this.