Removed usage line docs [ci skip]

Removes unnecessary comments from i18n validations tests [ci skip]

These comments do not add a lot to the readability, grepability or
overall understanding of the tests, therefore I believe they can be
safely removed.

fix class name typo [ci skip]

[ci skip] change sentence about reporting bugs in contributing guide

Improve duplicable documentation [ci skip]

Remove the reference to mocha in activemodel

Activemodel is no longer dependent on mocha, so we can make the comments
more generic.

constant loading should be thread safe now, so lets remove this

Concurrent load interlock (rm Rack::Lock)

See 2f26f611 for more info.

Also fix Minitest constant reference.

PATH_INFO is already set, so this branch will never execute.

we were already generating a path in the previous code (it was just not
returned), so lets just use the already computed path to popluate the
PATH_INFO header

Since we only work with new instances, these ivars will not be set.

We should call the setter on `path_parameters` so that we know the hash
will only contain the values that we've set.

I'd like to put all env mutations together so we can understand how to
change this code to call `call` on the controller

Since parameters are converted to a query string, they will
automatically be turned in to strings by the query parser

non_path_parameters is used internally (it never escapes this method) so
we should be able to safely use a regular hash.

since we are serializing parameters, we don't need to do all the dup
checks on each object.

We should roundtrip the parameters through their respective encoders /
decoders so that the controller will get parameters similar to what they
actually get in a real world situation

Require yaml for time_with_zone isolation test

Same fix as 109e71d2 but after
mocha got removed in 2f28e5b6.

pass in the instance variable to start decoupling the meat of the parser
from the instance of the middleware

We will always make an assignment to the env hash and eliminate a
conditional