Improve redis Swagger. Documenting list all patchSchedules to fix #2968. Documenting the CheckNameAvailability.type property better to fix #2967. And use a realistic timespan value in PatchSchedule examples.

Implementing suggested usability improvement for redis cache: by not modelling CheckNameAvailabilityParameters.resourceType as a string, it can instead be treated as a cosntant, so that the parameter becomes optional!

Backport to the Microsoft.cache/redis 2017-10-01 swagger (from 2018-03-01).