Fixed typos/copyediting

Minor typos and copyediting errors in documentation and docstrings.

Affected files:
  - README.rst
  - docs/source/news.rst
  - docs/source/2014-news.rst
  - docs/source/faq.rst
  - docs/source/settings.rst
  - gunicorn/config.py

Possible errors left uncorrected in gunicorn/config.py:
  - an incomplete sentence in the description of LimitRequestFieldSize (also in docs/source/settings.rst)
  - ambiguous phrasing in the description of ForwardedAllowIPS (also in docs/source/settings.rst)
  - ambiguous phrasing in the description of ProxyAllowFrom (also in docs/source/settings.rst)