Better acl rules message

[mrwulf]

Rule values were looking something like this:

rules: rules changed {'key' => {'' => {'policy' => 'read'}, 'othertree/qa2/' => {'policy' => 'write'}, 'testing/tree/qa2/' => {'policy' => 'write'}}} to 'keypolicywriteothertree/qa2/policywritetesting/tree/qa2/policywrite'

With this change, rule values show up as:

rules: rules changed '{"key"=>
{""=>{"policy"=>"write"},
"othertree/qa2/"=>{"policy"=>"write"},
"testing/tree/qa2/"=>{"policy"=>"write"}}}
' to '{"key"=>
{""=>{"policy"=>"read"},
"othertree/qa2/"=>{"policy"=>"write"},
"testing/tree/qa2/"=>{"policy"=>"write"}}}
'