Refactor AR distribution

* Deprecates AR1 distribution
* Implements random and moment methods
* Batching works on the left as with other distributions

Author: ricardoV94

pymc/distributions/__init__.py

@@ -102,7 +102,6 @@
 from pymc.distributions.simulator import Simulator
 from pymc.distributions.timeseries import (
     AR,
-    AR1,
     GARCH11,
     GaussianRandomWalk,
     MvGaussianRandomWalk,
@@ -169,7 +168,6 @@
     "WishartBartlett",
     "LKJCholeskyCov",
     "LKJCorr",
-    "AR1",
     "AR",
     "AsymmetricLaplace",
     "GaussianRandomWalk",