Moved the zmBandwidth option from a cookie to global Configure:: option

In addition I'm no longer passing this option around, instead calling it
where needed.  This _might_ fix #175 as the variable is being set very early on
in bootstrap.php
Use the global zmBandwidth variable from Configure::read in the layout
Merge pull request #190 from kylejohnson/modern

Moved zmBandwidth option from cookie to Configure:: option.  Might fix #175