non-UTF8 chars (like \u2013) in your map/reduce will make the ddoc fetch puke (#299)

* if for some reason you have non-UTF8 chars in your ddocs (like: \u2013) _Code.__new__ will puke.
to fix this I just added encoding to UTF8 before creating the UTF8 string to be returned

* fixed for non-string

Author: madmaze

CHANGES.rst

@@ -1,5 +1,6 @@
 2.5.0 (Unreleased)
 ==================
+- [FIXED] Fixed crash caused by non-UTF8 chars in ddocs
 - [FIXED] Fixed ``TypeError`` when setting revision limits on Python>=3.6.
 - [FIXED] Fixed the ``exists()`` double check on ``client.py`` and ``database.py``.
 - [FIXED] Fixed Cloudant exception code 409 with 412 when creating a database that already exists.

src/cloudant/_common_util.py

@@ -283,6 +283,8 @@ class _Code(str):
     codifying map and reduce Javascript content.
     """
     def __new__(cls, code):
+        if isinstance(code, unicode):
+            return str.__new__(cls, code.encode('utf8'))
         return str.__new__(cls, code)
 
 class InfiniteSession(Session):