Make coupled HMC avaiable at AdvancedHMC by default

[xukai92]

Options

• Porting codes to AdvancedHMC.jl
  • At least the maximal coupling part has no extra depedency
• Loading CoupledHMC from AdvancedHMC
  • We can make those needs JuMP depedency optional only when JuMP is loaded.