URI query decoding.

[CrowdHailer]

I am unclear why elixirs URL library does not support lists when encoding and decoding query strings

URI.decode_query("foo[]=1&foo[]=2")
# %{"foo[]" => "2"}
# But I would expect %{"foo" => ["1", "2"]} 

This is obviously a deliberate choice as in the docs is this quote

Keys and values can be any term that implements the String.Chars protocol, except lists which are explicitly forbidden.

elixir-lang/elixir#2876 Suggests just using plug but I will be instead copy and pasting as raxx cannot depend on plug.

[CrowdHailer]

Similar to #20 The specification for query parameters doesn't include nesting, however it doesn't to any degree specify what to do with multiple keys.

The solution is to write a URI2/Raxx.URI module.
Things to change:

• always return errors. URI.decode_www_form throws an error
• URI2.Query.decode() -> [{key => value}] both strings
• create a collapse to nested functionality

[CrowdHailer]

This is handled in version 0.6.0

[T-Spoon]

For anyone curious - URI2 is no longer part of this project - so decoding lists doesn't work as expected:

https://github.com/CrowdHailer/raxx/blob/19efea5e444e3a87fd8abee541dd0593ab0f782d/CHANGELOG.md#0150---2018-04-18