wsgiref compatibility fixes.

- Manually set env[‘REQUEST_URI’] (which is nonstandard) the same way
it’s set by uwsgi.
- Include HTTP error code reasons in error response. (wsgiref checks
that error code is at least 4 characters, i.e. includes reason)
wsgiref compatibility fixes.

- Manually set env[‘REQUEST_URI’] (which is nonstandard) the same way
it’s set by uwsgi.
- Include HTTP error code reasons in error response. (wsgiref checks
that error code is at least 4 characters, i.e. includes reason)
Merge branch 'master' of https://github.com/jcushman/pywb

Conflicts:
	pywb/utils.py
Merge pull request #3 from jcushman/master

wsgiref compatibility fixes