Replace dev.sh with tox environments

• install-all
• makemessages (@hansegucker)
• autopep8 (deprecated)
• pylama (deprecated)
• gource
• devstats-commits

removed milestone

mentioned in issue AlekSIS#32

changed the description

marked the checklist item autopep8 (deprecated) as completed

marked the checklist item pylama (deprecated) as completed

@nik and maybe also @all: Please evaluate which commands we still need.

Only makemessages, I guess. The rest is nice, but can be restored from the git history if we need it.

assigned to @hansegucker and unassigned @nik

created merge request !730 (merged) to address this issue

mentioned in merge request !730 (merged)

closed with merge request !730 (merged)

mentioned in commit 15bccea2