This makes sure that github.com/Azure/azure-sdk-for-go has the dependency it
requires: as of v14.6.0, it has a constraint for github.com/satori/go.uuid to be
at 1.2.0 (or above).
This was introduced in https://github.com/Azure/azure-sdk-for-go/pull/979
(see discussion for rationale)

Since github.com/Azure/azure-sdk-for-go is the only consumer of
github.com/satori/go.uuid, there is no reason not to use the correct version.

This also prepares the ground for a future migration to dep.