this eliminates the overuse of Connection#origin, which in the case of proxied connections was broken in the previous commit
the proxy implementation got simpler, despite this large changeset
Options become a bunch of session and connection level parameters, and requests do not need to maintain a separate Options object when they contain a body anymore, instead, objects is shared with the session, while request-only parameters get passed downwards to the request and its body. This reduces allocations of Options, currently the heaviest object to manage.
The reference for a request verb is now the string which is used
everywhere else, instead of the symbol corresponding to it. This was an
artifact from the import from httprb, and there is no advantage in it,
since these strings are frozen in most use cases, and the
transformations from symbol to strings being performed everywhere are
prooof that keeping the atom isn't really bringing any benefit.
connections weren't being correctly initiated, as proxies were filtered
for the whole session based on URI.find_proxy for the first call. This
fixes it by:
* applying it to all used uris;
* falling back to proxy options instead;
* apply no_proxy option in case it's used, using
`URI::Generic.use_proxy?
class overrides
the faraday adapter was relying on subclassing the session to load
custom plugins. this doesn't play well with other integrations
monkeypatching the original session class, such as datadog or webmock,
which redefine it. from now on, we not only defer the creation of the
custom until necessary, we also use Session#plugin
Fixes#187
