Fix #257, "org.scalatra.ForceHttps" set to true, if --https=true

ScalatraBase.redirect() use "org.scalatra.ForceHttps" in servlet
context init parameter when choice 'http' or 'https'.
Merge pull request #264 from bati11/257-https-reverse-proxy

Fix #257, "org.scalatra.ForceHttps" set to true, if --https=true