Bugfix and move plugin to python specific ftplugin

Move to python specific plugin (ftplugin),
Fixed bug regarding empty buffer.

ftplugin/python/test_py_example.py

@@ -0,0 +1,42 @@
+import os
+
+
+class Foo(object):
+    """Some doc"""
+    CLASS_ATTR = {"dict": 1,
+                  "bla": "foobar"}
+
+    def __init__(self, arg):
+        """initializaion"""
+        self.arg = arg
+
+    def method(self, x, y):
+        """very important method"""
+
+        def inner_funtion(x, y):
+            for i in y:
+                x = x + i
+
+            result = y[:]
+            result.append(x)
+            return result
+
+        result = None
+        result2 = """\
+multiline
+string
+the
+annoying
+bastard"""
+
+        if self.arg < 100:
+            result = inner_funtion(x, y)
+
+        return result if result else result2
+
+def main():
+    instance = Foo(10)
+    print(os.path.curdir, instance.method(2, [1, 2, 3]))
+
+if __name__ == "__main__":
+    main()