Add 'fixed' option to nav bar; bugfixes

* when 'fixed' is set in the xml on the navbar element, the navbar will appear fixed,
  however, it has to be the very first element in the document in this case
* bugfix (Go button triggers Search action)
* bugfix (duplicate ids when using pagetools and searchbar components twice)

Change-Id: Ief29fe6acfe93065c5c7ad63afda030a71c53e8f