Corrected typo in dublincore.py

Author: susca

extruct/dublincore.py

@@ -12,7 +12,7 @@
     'format': 'http://purl.org/dc/elements/1.1/format',
     'identifier': 'http://purl.org/dc/elements/1.1/identifier',
     'language': 'http://purl.org/dc/elements/1.1/language',
-    'publisher': 'http://purl.org/dc/elements/1.1/publiser',
+    'publisher': 'http://purl.org/dc/elements/1.1/publisher',
     'relation': 'http://purl.org/dc/elements/1.1/relation',
     'rights': 'http://purl.org/dc/elements/1.1/rights',
     'source': 'http://purl.org/dc/elements/1.1/source',