Inital steps towads scaling
Merge branch 'master' into scaling

Conflicts:
	chemreac/util/plotting.py
Move scaling example to examples
Steady state demo inplace.
DOC: Include steady_state example in documentation.
steady_state -> steady_state_approx
Re-add old steady state example
Merge pull request #7 from bjodah/scaling

Steady state example
Add pre-commit.sh
Better tests, docs, PEP8 compliance

- TST: reintroduce run_tests.sh in ./scripts/
- TST: Better test selection
- DOC: Update docs for steady_state_approx.