Replaced overly complex macro with a more "straight forward" solution.

Original implementation was owed to some misconceptions about
quoting/unquoting in macros.
Support for the definition of a "boot" hook function.

A boot hook is supposed to be called when an app is booted. A valid hook is
a one-arg function that will be passed the app's config as provided through
fm.websockets.app.config/defapp.
Extracted quoting of config values to helper function.
Removed unused dependency.
Optionally load and add a boot hook to the config.
Return the result of applying the boot hook as config.

Full control of what will be the app's config is transferred to the boot
hook (if any is configured...).
Support for attaching a config to a connection.
Add the booted config to each new connection.

Enables services to augment the app's config as required in their boot
hooks. The augmented config will then be added to each newly established
connection's resources.
Define a boot hook to augment the app's config.

Prepare the root directory for uploaded files in the boot hook and add id
to the app's config. It can then be accessed from within rpc targets during
an upload.