Proxy: default to accepting any method

[nox-4O4]

Currently, only GET requests are allowed when the methods field is not specified. This does not match documented behaviour:

janus/docs/proxy/request_http_method.md

Lines 3 to 6 in aa38d13

	Client requests can also be routed depending on their
	HTTP method by specifying the `methods` field. By default, Janus will route a
	request to an API regardless of its HTTP method. But when this field is set,
	only requests with the specified HTTP methods will be matched.

This PR makes the proxy default to accepting any method.