Added examples and backends to setup.py to address #531
Remove `pymc.backends` from package list

This relates to an unmerged PR and was unintentionally added in previous
commit.
Fixed examples install issue #531
Added __init__.py to examples/data
Install test data alongside examples; fixes https://github.com/pymc-devs/pymc/issues/531
Merge pull request #533 from andrewclegg/examples_install

Install test data alongside examples; fixes https://github.com/pymc-devs...
Merge branch 'master' into examples_install

Conflicts:
	setup.py
Merge branch 'examples_install'