Add commit field for bypassing verification (--no-verify)

This new field toggles whether or not we will pass --no-verify to `git
commit'.

Default keybinding: C-c C-n
magit-cmd-output: do not corrupt output

This fixes #544.  There is no reason why we would want to manipulate
git's output.  In the master and next branches something similar to
the code removed in this commit was used to have colorful graphs in
logs, but in maint that isn't the case.
Merge pull request #641 from tarsius/maint

magit-cmd-output: do not corrupt output
Merge branch 'tarsius/colour'
Merge branch 'maint'
Merge branch 'master' into next
Merge pull request #643 from tarsius/quiet

quiet byte-compiler and make
Merge pull request #642 from tarsius/tests

tests/run-tests.el: add /path/to/magit/../{mocker,cl-lib} to load-path
do not activate magit specific font-lock keywords

We haven't decided yet how to best activate these keywords.
So for now users have to activate manually in all elisp files:

    (font-lock-add-keywords 'emacs-lisp-mode
                            magit-font-lock-keywords))
Merge branch 'font-lock-keywords' into next
Merge branch 'maint' of git://github.com/nonsequitur/magit into maint
Merge branch 'maint'
Merge branch 'master' into next
magit-simple-keys.el: fix typo in commentary
magit-classic-theme.el: add library header
Merge branch 'cleanup'
Merge branch 'master' into next
README.md: put extensions in own section, push it down
README.md: link to up-to-date contributors list on github

Also prettify link to the owners team.
README.md: fix links