Update install.rst

I noticed on the website that the documentation regarding Debian was aging, so I took the liberty of adding some new content and making modifications to the source here. I used the existing content as a template to expand the Debian installation section to account for the recent changes.

Debian "wheezy" was released in May 2013 moving "squeeze" to "oldstable" status.

I hope this helps.
Fix to read the settings module specified by --settings or django_settings parameter
try to use cwd() + gunicorn.conf.py as default config if no file is specified . see #52
Add Upstart deployment example, remove Upstart from faq.

Add an Upstart deployment example and remove the Upstart entry in the
FAQ.
Add post-init hook for workers

Allows a config specifying a function after a worker has been initialized and before the run loop
Fix capitalization
Add docs for post_init
Merge pull request #555 from seatgeek/post-init

Add post-init hook for workers
add Philip Cristiano to THANKS
Merge pull request #553 from romabysen/master

Add Upstart deployment example, remove Upstart from faq.
Rename post_init for greater clarity

Makes sense if you saw what it does, less if you just read the config option.
Merge pull request #556 from seatgeek/post-init

Rename post_init for greater clarity
[gunicorn] added ```gunicorn.conf.py``` as default in case of no -c is specified
prevent call get_default_config_file if args.config exists
Added coverage for get_default_config_file, also a test for default config overrides
Merge pull request #552 from niedbalski/master
Add niedbalski to THANKS
give the initial global_conf to loadcontext to initialize the context properly.
add Moriyoshi Koizumi to THANKS
fix syslog in 2.6

socktype is only supported in 2,7 and sup.

fix #541