typos
pyflakes fixes
Merge pull request #373 from SimTk/pyflakes

pyflakes fixes
remove stuff from setup
Bring in the knife
Update requirements
add info to setup about dependencies
retrigger ci
change travis to use conda mdtraj (will be faster, no extra compilation)
Merge pull request #375 from SimTk/remove-contact

Remove the remaining c extension modules
update installation docs
Merge pull request #378 from SimTk/installation

update installation docs
fix after_sucess
merge