feat(CLI): --debug flag to output traffix

* If `--debug` is set, we will output all server communication to
  stderr. That way, we can compare our requests to what is expected by
  ush based on official docs.
* `discovery` now doesn't use the API key anymore - this is specified
   using a custom override.

Nice, we are totally ready to test and fix all API features.

Related to #70

etc/api/discovery/v1/discovery-api_overrides.json

@@ -0,0 +1,3 @@
+{
+	"no_auth": 1
+}

etc/api/type-cli.yaml

@@ -29,5 +29,6 @@ cargo:
     - docopt = "*"
     - docopt_macros = "*"
     - rustc-serialize = "*"
+    - yup-hyper-mock = "*"
     - serde = ">= 0.3.0"
     - serde_macros = "*"

src/mako/api/lib/mbuild.mako

@@ -325,7 +325,7 @@ ${capture(lib.test_hub, hub_type_name, comments=show_all) | hide_filter}
 // As the method needs a request, you would usually fill it with the desired information
 // into the respective structure. Some of the parts shown here might not be applicable !
 // ${random_value_warning}
-let mut ${rb_name}: ${request_value_type} = Default::default();
+let mut ${rb_name} = ${request_value_type}::default();
 % for spn, sp in request_value.get('properties', dict()).iteritems():
 % if parts is not None and spn not in parts:
 <% continue %>
@@ -579,6 +579,7 @@ else {
         let mut url = "${baseUrl}${m.path}".to_string();
         % endif
         % if not default_scope:
+        % if no_auth is UNDEFINED:
         <% 
             assert 'key' in parameters, "Expected 'key' parameter if there are no scopes"
         %>
@@ -593,6 +594,7 @@ else {
                 return Err(Error::MissingAPIKey)
             }
         }
+        % endif
         % else:
         if self.${api.properties.scopes}.len() == 0 {
             self.${api.properties.scopes}.insert(${scope_url_to_variant(name, default_scope, fully_qualified=True)}.as_ref().to_string(), ());

src/mako/cli/lib/docopt.mako

@@ -66,5 +66,8 @@ Configuration:
             A directory into which we will store our persistent data. Defaults to a user-writable
             directory that we will create during the first invocation.
             [default: ${CONFIG_DIR}]
+  --debug
+            Output all server communication to standard error. `tx` and `rx` are placed into 
+            the same stream.
 ");
 </%def>

src/mako/cli/lib/engine.mako

@@ -112,9 +112,18 @@ self.opt.${cmd_ident(method)} {
                                         program_name: "${util.program_name()}",
                                         db_dir: config_dir.clone(),
                                       }, None);
+
+        let client = 
+            if opt.flag_debug {
+                hyper::Client::with_connector(mock::TeeConnector {
+                        connector: hyper::net::HttpConnector(None) 
+                    })
+            } else {
+                hyper::Client::new()
+            };
         let engine = Engine {
             opt: opt,
-            hub: ${hub_type_name}::new(hyper::Client::new(), auth),
+            hub: ${hub_type_name}::new(client, auth),
         };
 
         match engine._doit(true) {

src/mako/cli/main.rs.mako

@@ -16,6 +16,7 @@
 
 extern crate docopt;
 extern crate yup_oauth2 as oauth2;
+extern crate yup_hyper_mock as mock;
 extern crate rustc_serialize;
 extern crate serde;
 extern crate hyper;
@@ -33,12 +34,13 @@ fn main() {
     let opts: Options = Options::docopt().decode().unwrap_or_else(|e| e.exit());
     match Engine::new(opts) {
         Err(err) => {
-            write!(io::stderr(), "{}", err).ok();
+            writeln!(io::stderr(), "{}", err).ok();
             env::set_exit_status(err.exit_code);
         },
         Ok(engine) => {
             if let Some(err) = engine.doit() {
-                write!(io::stderr(), "{}", err).ok();
+                writeln!(io::stderr(), "{:?}", err).ok();
+                writeln!(io::stderr(), "{}", err).ok();
                 env::set_exit_status(1);
             }
         }