fix(discovery): handle discovery urls with $

Some google discovery URLs contain `$discovery` or other variants,
causing the calls to wget to interpret `$d` as an environment variable
instead of a literal. An example is:
`https://logging.googleapis.com/$discovery/rest?version=v2`.

To fix this, the `$` has been escaped so that wget fetches the URL as
expected.

src/mako/deps.mako

@@ -179,11 +179,14 @@ help${agsuffix}:
 	target = target_dir + '/' + name + '-api.json'
 	## assure the target never actually exists to force him to wget whenver we ask !
 	fake_target = target + '-force'
+	## Some service urls have $ in them. This may cause the console to treat them as env vars.
+	## To handle this properly, we need to escape the $.
+	url = info['discoveryRestUrl'].replace("$", "$$")
 	json_api_targets.append(fake_target)
 %>\
 ${fake_target}:
 	@mkdir -p ${target_dir}
-	@-wget -nv ${info['discoveryRestUrl']} -O ${target}
+	@-wget -nv '${url}' -O ${target}
 % endfor
 
 update-json: ${' '.join(json_api_targets)}