Add flake8 in tox
Add flake8 in tox

Signed-off-by: Julien Danjou <5c682c2d1ec4073e277f9ba9f4bdf07e5794dabe@danjou.info>

gilch/hy,mtmiller/hy,larme/hy,kirbyfan64/hy,algernon/hy,Tritlo/hy,timmartin/hy,paultag/hy,tianon/hy,larme/hy,freezas/hy,Foxboron/hy,aisk/hy,kirbyfan64/hy,zackmdavis/hy,kartikm/hy,farhaven/hy,tianon/hy,aisk/hy,larme/hy,tianon/hy,hcarvalhoalves/hy,farhaven/hy,farhaven/hy,jakirkham/hy,adamfeuer/hy,ALSchwalm/hy,Foxboron/hy,michel-slm/hy,aisk/hy,hcarvalhoalves/hy,tuturto/hy