Don't reference multiresult dict directly

Change-Id: I17560cc49bc89dd18d46d03f3c6614b3e4e97a49
Basic PyPy support

This commit adds some basic changes to the extension to allow basic
usage and compilation with PyPy. The pypy support is *STILL BUGGY* and
should not be used in production environments. However basic operations
seem to be working. Tests however, seem to still fail.

Change-Id: Ia56e11e656988894d84dec2fb5bd7f9bd8a8a9e9
Skip some tests on PyPy

Change-Id: If1824a9b4d0138a39408d3ed947a7eaa2b797f19
PyErr_Clear if GetAttr fails

Change-Id: Ic6d889e2918467997e64295e7f28e0548da1c1cd
Documentation for async interface

Change-Id: I940ac2765092e5e6918dcd7ed96195c84ef0e845