validate keywords from thesaurus

the issue has 3 goals:

• verify that keywords from a thesaurus can be submitted (as uri)
• if people submit a keyword from a thesaurus, verify the keyword exists on the thesaurus, if not, warn email notification?) or try to correct
• if people submit a plain keyword, verify if it matches with a keyword from a thesaurus, then move it to the thesaurus, or suggest to move it (email notification?)