Filtering mechanism

There is now an ability to set excluding filters (in runtime or when initializing) so that some of the results (controllers or methods) would be ignored (e.g. filtered by api version or device).
Excluding with @ApiExclude uses this mechanism from now and could be used as an example.

Usage:
    <bean class="com.knappsack.swagger4springweb.controller.ApiDocumentationController">
      ..      
      <property name="filters">
        <list>
          <ref bean="filter1"/>
          <ref bean="filter2"/>
        </list>
      </property>
    </bean>

Or they could be added "on the go" using setFilters(..)