JCLOUDS-188: Include pagination parameters in Abiquo VirtualMachineTemplateOptions

* Modified the Abiquo VirtualMachineTemplateOptions builder to inherit from the BaseFilterOptionsBuilder so it can accept pagination parameters.
* Also superseded the OrderBy enum by a simple String, to avoid hardcoding the fields that are suitable to be sorted.
* The OrderBy enum has been removed and the FilterOptions class moved to a more convenient package.