server: Make flask methods more modular.

Split the collection of GSettings data into a separate "collector"
class (for lack of a better word).  This makes room for collecting
data from other types of loggers snooping in the embedded session.

The collector "API" at this point is only a rough guess.
server: Append a variable to the 'submit_change' route.

Need to distinguish submissions from multiple loggers, so extend the
submission path to '/submit_change/<name>' where <name> is equivalent
to the JSON profile settings name (e.g. org.gnome.gsettings).
logger: Add a GoaLogger class.

GoaLogger class is for GNOME Online Accounts.  It monitors the file
~/.config/goa-1.0/accounts.conf and relays updates to the HTTP server.

The accounts.conf content is read by Python's ConfigParser module,
filtered, and converted to JSON format prior to submission.  The HTTP
server receives the request and uses the JSON data verbatim in building
the final JSON profile.