Simple browser-based network configurator

Using Sinatra and Haml for the browser interface. Back end is Debian's
/etc/network/interfaces, via an intermediate configuration file.
Add JavaScript to show/hide appropriate forms
Changed some h1s to h2s and h3s
Move around some routes and authentication

This moves the network config page to /netconfig and makes authentication
a bit more granular. This will allow building in a local web page for the
full screen browser to point at.
got off on a bit of a roll...
Comments, lots of comments everywhere
More comments and information
clean up and comment netconfig.rb (untested!)
write the actual interfaces file, not stdout
Put network config stuff in module ConcertoConfig
writing code, not committing...

updated concerto_config_server because routes got inconsistent and
needed to add module namespace to a few things. Fixed problem.js
to redirect to proper route. Fixed problem.haml to include link
to setup page. Make setup page form actually work.
More fixes as things are moved to ConcertoConfig

also move a few more things over there
fix some bugs that turned up on the live system
build in a default configuration
Package everything up as a gem
Move raw file I/O out into a ConfigStore module
move remaining file I/O logic out of app.rb
Added a change password form

Also added helpful links on the setup page.
This is 0.0.2.
darn you Ruby, repackaging my exceptions...

Ruby's Tempfile class repackages file I/O exceptions to RuntimeErrors.
This was causing ConcertoClient::LiveImage.readonly? to fail when the
filesystem was actually readonly. Now, any exception is taken to mean
that the filesystem is readonly.
bin/concerto_netsetup: use new function name

this script was broken by an earlier commit