Adding specs for SAUTHC1_SIGNER
get_resource now accepts query hash
Building an association spec to show expand functionality

- exposing request_executor to allow for expectations in spec

- "get" method now accepts an optional expansions hash

- adding spec
Adding resource expansion

- call to "get" now accepts an optional instance of Stormpath::Resource::Expansion

- adding tests codifying transmute of Expansion to Hash (suitable for serializing to query string)

- adding tests to client_spec that verify nested, expanded resources are cached on load

- updating collection spec to assert on state of criteria hash
Merge branch 'features/support_entity_expansion_qs_params-36' into development