Plugins may contribute to the /plugins/NAME/ URL space by providing
a ServletModule in the manifest using Gerrit-HttpModule and binding
servlets and filters using Guice bindings.
All names are relative to the plugin's directory, so
serve("/").with(IndexServlet.class);
will handle /plugins/NAME/ and not "/" on the server. This makes a
plugin automatically relocatable to match its SSH command name or
the name in $site_dir/plugins.
Change-Id: I17e3007f0310d2bf4989d652f18864a77c5d5f2e
2aefecf604