Use importlib instead of __import__
BF: Add backport of importlib for python 2.6
Merge pull request #1 from arokem/stefanv-importlib

ENH: Backport importlib
BF: Relative import
BF: Absolute import instead.
BF: Remove the import that was not in the try clause.
Merge pull request #2 from arokem/stefanv-importlib

BF: Relative import
Merge pull request #471 from stefanv/importlib

Use importlib instead of __import__