fix initialization of cache store extensions
fix initialization of cache store extensions

they need to happen before initializing the cache, not after
initializing AR

Change-Id: I90842cba032e4fffa4332d66d6b0adf0ef2665b6
Reviewed-on: https://gerrit.instructure.com/32249
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

krrg/switchman,instructure/switchman,ccutrer/switchman,instructure/switchman