Change default for `:absolute-redirects` to `false`

[jumarko]

As I mentioned on slack
I'd love to see if absolute redirects were not enabled by default.

The original HTTP spec that mandated this has been replaced by a newer version about 8 years ago.
This is causing problems for people running web apps behind load balancers and proxies terminating TLS.
See clj-commons/friend#4 and clj-commons/friend#5

[jumarko]

@weavejester any thoughts on this?

[weavejester]

Apologies for the delay. I've been a little swamped recently. I think this is fine, and I'd welcome a PR.

[jumarko]

Here's the PR: #40
Thanks!