Add RIS parser

gargantext/parsers/__init__.py

+from .ris import RISParser

gargantext/parsers/ris.py

+from RISparser.parser import Ris
+from RISparser.config import TAG_KEY_MAPPING
+
+
+# See https://github.com/MrTango/RISparser/blob/master/RISparser/config.py
+GARGANTEXT_KEY_MAPPING = dict(TAG_KEY_MAPPING, **{
+    'PY': 'publication',
+    'N1': 'references',
+    'LA': 'lang',
+    'JO': 'source',
+    'ST': 'subtitle',
+    'Y2': 'secondary_publication',
+})
+
+
+class RISParser(Ris):
+    PATTERN = '^[A-Z][A-Z0-9]  -'
+
+    def __init__(self, lines):
+        super().__init__(lines, GARGANTEXT_KEY_MAPPING)