Add support to complex language range in keyword search

[fxp]

Currently, GeoNetwork use 2 letters code and search for keyword in current GUI language. If thesaurus use more complex language range (rfc4647), keyword search return nothing.

Example:

 <skos:Concept rdf:about="http://vocab.nerc.ac.uk/collection/A02/current/Education">
        <dc:identifier>SDN:A02:3:Education</dc:identifier>
        <skos:prefLabel xml:lang="en-GB">Public Education</skos:prefLabel>
        <skos:altLabel/>
        <skos:definition xml:lang="en-GB">Public Education</skos:definition>
        <skos:comment>accepted</skos:comment>
        <dc:date>2011-08-15 11:58:51.0</dc:date>
        <skos:broadMatch
            rdf:resource="http://vocab.nerc.ac.uk/collection/A01/current/Legislation_and_Policy"/>
        <skos:broadMatch rdf:resource="http://vocab.nerc.ac.uk/collection/A03/current/Research"/>
        <skos:broadTransitive
            rdf:resource="http://vocab.nerc.ac.uk/collection/A01/current/Legislation_and_Policy"/>
        <skos:broadTransitive rdf:resource="http://vocab.nerc.ac.uk/collection/A03/current/Research"
        />
    </skos:Concept>

Changes: Use wildcard operator to support more complex language range syntax. Example search for en* will match xml:lang="en-GB"

[fxp]

Committed revision 8474.