- before_kill, after_kill hooks introduction
- add a system to pass extra parameters to hooks (to be able to pass the
  process pid to before/after_kill)
before/after_kill => before/after_signal (better)
SIGKILL is always sent
documentation update
add some tests for before_signal and after_signal hooks
add more documentation and examples for hooks
PEP8 compliance

That extra line was breaking the build.
started a supervisor page
remove all parenthesis here as @tarekziade proposed
Update supervisor.rst

Fixed some typos & added references
Removed Travis skips
more details on supervisor streams
unused import
Merge branch 'master' of https://github.com/thefab/circus