Fix api_base URL scheme to detect SSL

[migurski]

URLs in the API docs say http:// even on an SSL page. We’ll need to revisit the use of request.scheme in app.py so it correctly picks up the new schema for display, even when proxied behind Apache.

Context in https://github.com/codeforamerica/codeforamerica.org/issues/529#issuecomment-72798885.

[ondrae]

@tmaybe and I have been tracing this out.

There is a clue at http://stackoverflow.com/a/24920818/722860 about making an addition to Apache. @migurski What say you?

[tmaybe]

here are the current headers we're getting on an https request (I removed Cookie and User-Agent):

X-Forwarded-Port: 80
X-Forwarded-For: 69.12.169.82, 54.234.33.69
Pragma: no-cache
X-Request-Id: cc29f5ca-f65c-43f6-882b-f9654450ba47
X-Request-Start: 1423091731285
X-Forwarded-Proto: http
X-Forwarded-Server: codeforamerica.org
Cache-Control: no-cache
Accept-Language: en-US,en;q=0.8,id;q=0.6
Host: www.codeforamerica.org
Accept-Encoding: gzip, deflate, sdch
Via: 1.1 vegur
Total-Route-Time: 0
Connect-Time: 0
Connection: close
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Gecko) Chrome/40.0.2214.91 Safari/537.36

[tmaybe]

See also: http://flask.pocoo.org/snippets/35/

[migurski]

I can definitely add a new request header to the main proxy config. Want to put our heads together on this tomorrow?

[tmaybe]

yeah! let's do it