Refactor spec of indifferent params access

This version describes the behavior that we want ("I get the same value
back regardless of whether I use a String or a Symbol as a key"),
rather than the state of the params hash itself.
Change #inject to #each_with_object
WIP: Introduce Rory::HashWithDubiousSemantics
TDD the [] and []= bits of HashWithDubiousSemantics
Merge pull request #2 from geeksam/hash-with-dubious-semantics

Add Rory::HashWithDubiousSemantics