fix(uwsgi): Fix broken uWSGI config (#237)

This patch introduces the following fixes to uWSGI config which
was not set up correctly to be used publicly (not behind a router,
load balancer, proxy like nginx etc.):

• Use http option for a front-proxy
• Set protocol back to uwsgi due to above
• Prevent forced socket binding to uwsgi due to protocol change above (https://git.io/fj7Lw)
• Turn on "keep-alive" support

Should fix getsentry/sentry-cli#40.