resolveResponse() mutates its input

[John Ruble]

Despite going through the trouble of making a copy:

contentful-resolve-response/index.js

Line 155 in c6ef571

 const responseClone = copy(response) 

It seems that resolveResponse() is mutating its input.

See associated PR for a failing test.

[John Ruble]

Here's a one-line changes that fixes the unit test, but I haven't tested the change with a real app:

jrr@e24524a