issue #10: added basic test of the web app and the Bookmark class
To make the application testable, BookmarksApp now does not require a
config_file to be set, and can just be configured via a config hash in the
constructor. In addition, authentication and reverse proxy rewriting are now
conditionally enabled based on whether there is an auth and proxy_ip key in
the config, respecitvely.
Added Plack 1.0036 to the cpanfile dependencies, since that is the version that
contains Plack::Test.
Also fixed the Bookmarks::create_tables() method to load the
bookmarks.sql file from the correct location.
