Added a check to make sure the from parameter redirect is a relative url

This should protect against an open redirect attack. See

https://www.owasp.org/index.php/Open_redirect
Revert 336a198..d06a688

This rolls back to commit 336a1988cdcefebf5e5f1b1f924427b753ab54f6.
Added a test for the from querystring parameter to ensure it is a relative address.

This is protect the user against an open redirect attack.  See this
page for more details -
https://www.owasp.org/index.php/Top_10_2013-A10-Unvalidated_Redirects_an
d_Forwards
Merge pull request #242 from oliverjenkins/master

The from parameter redirect on signin is not validated and allows for open redirects.