Thomas Graff: Patch to fallback to default value instead of showing error when...

Thomas Graff: Patch to fallback to default value instead of showing error when invalid boolean format set on ispassive or forceauthn

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@1487 44740490-163a-0410-bde0-09ae8108e29a