• adds application/json as a content type for with_json_body calls
• Prevented ibrowse options from flattening in HTTPotion calls
• updated documentation for easier copy/paste

• Fixed typo in HTTPoison adapter, delegating to fixed message with depreciation warning.

• Added hackney as an optional dependancy.

This push has breaking changes from 0.1.1

Changes:

• Removed types on the response for HttpBuilder.Adapter, to be more flexible around errors.
• Removed types on HTTPoison adapter so it doesn't assume response format.

Additions:

• Add HTTPoison adapter.

• Add IBrowse adapter.

• Add Hackney adapter.

• Add JSON Parser adapter, supporting Posion.

• Added with_json_body option.

• Added with_string_body option.

• Added marker to with_body to avoid namespace collision

Deletions:

• removed retry for now, until a proper backoff implementation can be added.
• removed explicit streaming (implicitly still supported), as adapter cannot reasonably abstract all possible combinations.