Revert "Better headers and better caching Fix #273"

Reverts webcompat/webcompat.com#295

I see a lot of this when running tests: `KeyError: 'HTTP_IF_NONE_MATCH'`
```
127.0.0.1 - - [02/Oct/2014 10:54:52] "GET /issues/200 HTTP/1.1" 200 -
127.0.0.1 - - [02/Oct/2014 10:54:52] "GET /api/issues/200 HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/mtaylor/dev/compat/webcompat.com/webcompat/api/endpoints.py", line 59, in proxy_issue
    issue = proxy_request('get', '/{0}'.format(number))
  File "/Users/mtaylor/dev/compat/webcompat.com/webcompat/issues.py", line 36, in proxy_request
    etag = g.request_headers['If-None-Match'].encode('utf-8')
  File "/Users/mtaylor/dev/compat/webcompat.com/env/lib/python2.7/site-packages/werkzeug/datastructures.py", line 1278, in __getitem__
    return _unicodify_header_value(self.environ['HTTP_' + key])
KeyError: 'HTTP_IF_NONE_MATCH'
```