Indentation to 4 spaces / PEP8 / import missing fix

This pull request makes the code PEP8 compliant (give or take) and converts indentation to 4 spaces (like Guido indented it).

Import are rewritten to relative style to actually know what comes from where (`import exception` => `from . import exception`). This results in scripts not being executable as scripts anymore, but only as modules (`python zeit/api/tests.py` => `python -m zeit.api.tests`).

 This fixes at least one missing import bug. Minor code smells like *-imports, locals() and equal comparisons to `None` and `True` were also fixed.

Sorry for being the PEP8/4 spaces nazi.