v1.0.0-beta3

• [Breaking] Environment config provider was removed. If you were using
  environment variables to override YAML values, see
  config documentation for more information.
• [Breaking] Simplify Provider interface: remove Scope method from the
  config.Provider interface, one can use either ScopedProvider and Value.Get()
  to access sub fields.
• Add task.MustRegister convenience function which fails fast by panicking
  Note that this should only be used during app initialization, and is provided
  to avoid repetetive error checking for services which register many tasks.
• Expose options on task module to disable execution. This will allow users to
  enqueue and consume tasks on different clusters.
• [Breaking] Rename Backend interface Publish to Enqueue. Created a new
  ExecuteAsync method that will kick off workers to consume tasks and this is
  subsumed by module Start.
• [Breaking] Rename package uhttp/client to uhttp/uhttpclient for clarity.
• [Breaking] Rename PopulateStruct method in value to Populate.
  The method can now populate not only structs, but anything: slices,
  maps, builtin types and maps.
• [Breaking] package dig has moved from go.uber.org/fx/dig to a new home
  at go.uber.org/dig.
• [Breaking] Pass a tracer the uhttp/uhttpclient constructor explicitly, instead
  of using a global tracer. This will allow to use http client in parallel tests.