review and document recommended way of developing with bitmask ui + pixelated
Definition of done
a new page in bitmask docs/ dedicated to ui + pixelated development. could merge parts of the README.rst that deal with developing ui.
right now there's no single place that documents setting up a development environment that allows to develop on pixelated. I don't think the generic pixelated devenv is suitable for us; we should focus on a virtualenv-base env (recommend pew I think).