Ensure java.io.tmpdir is available before using it

Some environments do not have a tmpdir so it can be null.
Minor fixes in howto documentation re:SSL config

Fixes a couple of typos in the documentation:
* `x-forwarded-protocol` is not the standard name for this header
* `require_https` is not an existing property, but rather `require_ssl`
Merge branch '1.1.x'