Merge tag 'sparks-3.7.8' into develop

3.7.8
pep8 cleanups.
django forms restricted file field.
prefix the south migration with 'yes', else Fabric stops in the middle.
Make `nice` and `ionice` commands be parameterable, and sparks defautls overridable with an env variable.
bump version in __init__.py
Merge branch 'release/3.8'