Minor updates to pj-trace-redir.js.

 * UA setting consistent with newer PhantomJS
 * log onLoadFinished
 * include the complete event log in the JSON output
 * if --capture, capture page content regardless of whether page load was
   officially successful (so we get 404 pages and the like, too).
Minor updates to openvpn-netns.

 * Use getauxval(AT_EXECFN) to determine the full path to the executable;
   argv[0] isn't necessarily an absolute path.
 * To signal that the VPN is ready, write "READY\n" to stdout before
   closing it, so that the supervisor can distinguish this from stdout
   being closed because the VPN *failed* to come up and the program has
   now exited.  (I really should have thought of that before.)
Revise capture for multiple proxy methods & newer database schema.

 * Can now ask for a direct connection, ssh connection, or openvpn
   connection.
 * Record the HTTP log now produced by pj-trace-redir.
 * Much simpler and faster way of handling "have we done this URL yet in
   this locale?"
 * No longer relies on canonize having been run first; indeed, canonize is
   no longer a thing in the new database schema.
Document the new database schema.

Nothing actually *uses* this file, you have to manually set up the
database before any of the url-source programs work.  Also, nothing
validates that the schema is as expected.  This is more flying without
a net than I am comfortable with, but I don't have time to reengineer
the entire system using SqlAlchemy or similar, and I haven't yet found
an "or similar" that actually believes in schema validation.  (Surely
no one would write production systems for which critical data structure
specifications were not enforced by code in source control?  Surely?)
Update some of the URL sources for the new database schema.

Specifically, s_citizenlab is responsible for populating the
clab_categories table, and the canon queue is no longer a thing.