BF: add top-level benchmarking command

This allows ``import dipy; dipy.bench()``
Merge pull request #136 from matthew-brett/add-top-level-bench

BF: add top-level benchmarking command
Merge pull request #137 from MrBago/fix_allclose_error

BF - check shapes before allclose
Coding style fix for dsi_deconv
Merge pull request #138 from mpaquette/dsi_deconv_fix_codestyle

Coding style fix for dsi_deconv