Improve compression by removing whitespace from separators when using jsonify() and JSONIFY_PRETTYPRINT_REGULAR is False.

Commit includes Changelog entry and two new tests in test_basic.py.

flask/json.py

@@ -227,15 +227,22 @@ def jsonify(*args, **kwargs):
     This function's response will be pretty printed if it was not requested
     with ``X-Requested-With: XMLHttpRequest`` to simplify debugging unless
     the ``JSONIFY_PRETTYPRINT_REGULAR`` config parameter is set to false.
+    Compressed (not pretty) formatting currently means no indents and no
+    spaces after separators.
 
     .. versionadded:: 0.2
     """
+
     indent = None
+    separators = (',', ':')
+
     if current_app.config['JSONIFY_PRETTYPRINT_REGULAR'] \
        and not request.is_xhr:
         indent = 2
+        separators = (', ', ': ')
+
     return current_app.response_class(dumps(dict(*args, **kwargs),
-        indent=indent),
+        indent=indent, separators=separators),
         mimetype='application/json')