[mod] Add searx.data module

Instead of loading the data/*.json in different location,
load these files in the new searx.data module.

searx/data/__init__.py

@@ -0,0 +1,21 @@
+import json
+from pathlib import Path
+
+
+__init__ = ['ENGINES_LANGUGAGES', 'CURRENCIES', 'USER_AGENTS', 'bangs_loader']
+data_dir = Path(__file__).parent
+
+
+def load(filename):
+    # add str(...) for Python 3.5
+    with open(str(data_dir / filename), encoding='utf-8') as fd:
+        return json.load(fd)
+
+
+def bangs_loader():
+    return load('bangs.json')
+
+
+ENGINES_LANGUAGES = load('engines_languages.json')
+CURRENCIES = load('currencies.json')
+USER_AGENTS = load('useragents.json')