Remove six and all/any support for Python 2.

This time for real.

Author: arokem

nitime/__init__.py

@@ -26,6 +26,5 @@
 from . import algorithms
 from . import timeseries
 from . import analysis
-from . import six
 
 from .timeseries import *

nitime/analysis/base.py

@@ -1,8 +1,5 @@
 
-try:
-    from inspect import getfullargspec
-except ImportError:  # PY2
-    from inspect import getargspec as getfullargspec
+from inspect import getfullargspec
 
 from nitime import descriptors as desc