Absinthe.Phoenix.Socket.put_options/2 overwrites options, causes loss of custom adapter.

[alanpeabody]

Custom adapters & Absinthe.Phoenix.Channels do not work.

When using a custom adapter only the first request uses the adapter, subsequent request do not.

This happens due to the use of Absinthe.Phoenix.Socket.put_options/2 inside Absinthe.Phoenix.Channels.run_doc/4 - Absinthe.Phoenix.Socket.put_options/2 overwrites the entire :opts field.

Some simple solutions might be:

1. Use Map.merge instead of Map.put in put_options.
2. Manually preserve adapter as well as context in run_doc.
3. Add a merge_options or similar.

Let me know the preferred approach and I can open a PR.