Add support for OGC filters 2.0

**Working on WFS 2.0 integration in openlayers**

This PR adds support for OpenGIS Filter Encoding 2.0.
  * Provide new OpenLayers.Format.Filter.v2_0_0
  * Add test suite for this format
  * Temporal filters are not supported yet

Specifications :
http://portal.opengeospatial.org/files/?artifact_id=39968

Exemple :

    <fes:Filter
         xmlns:fes="http://www.opengis.net/fes/2.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://www.opengis.net/fes/2.0
         http://schemas.opengis.net/filter/2.0.0/filterAll.xsd">
        <fes:PropertyIsBetween>
            <fes:ValueReference>DEPTH</fes:ValueReference>
            <fes:LowerBoundary>
                <fes:Literal>100</fes:Literal>
            </fes:LowerBoundary>
            <fes:UpperBoundary>
                  <fes:Literal>200</fes:Literal>
            </fes:UpperBoundary>
        </fes:PropertyIsBetween>
    </fes:Filter>

Related PR - WFS 2.0 capabilities Format : https://github.com/openlayers/openlayers/pull/1058