Remove use of unicode_literals as it is an anti-pattern

from __future__ unicode_literals leads to developer confusion as
developers no longer can tell whether a bare literal string is a byte
string or a unicode string.  Explicit marking as u"" or b"" is the way
to solve the same problem in the Ansbile codebase.

lib/ansible/plugins/lookup/mongodb.py

@@ -88,7 +88,6 @@ EXAMPLES:
 '''
 
 from __future__ import (absolute_import, division, print_function)
-from __future__ import unicode_literals
 from ansible.module_utils.six import string_types, integer_types
 import datetime
 
@@ -120,7 +119,7 @@ class LookupModule(LookupBase):
             return sort_parameter
 
         if not isinstance(sort_parameter, list):
-            raise AnsibleError("Error. Sort parameters must be a list, not [ {} ]".format(sort_parameter))
+            raise AnsibleError(u"Error. Sort parameters must be a list, not [ {} ]".format(sort_parameter))
 
         for item in sort_parameter:
             self._convert_sort_string_to_constant(item)
@@ -130,9 +129,9 @@ class LookupModule(LookupBase):
     def _convert_sort_string_to_constant(self, item):
         original_sort_order = item[1]
         sort_order = original_sort_order.upper()
-        if sort_order == "ASCENDING":
+        if sort_order == u"ASCENDING":
             item[1] = ASCENDING
-        elif sort_order == "DESCENDING":
+        elif sort_order == u"DESCENDING":
             item[1] = DESCENDING
         # else the user knows what s/he is doing and we won't predict. PyMongo will return an error if necessary
 
@@ -159,13 +158,13 @@ class LookupModule(LookupBase):
             return (result - datetime.datetime(1970, 1, 1)). total_seconds()
         else:
             # failsafe
-            return "{}".format(result)
+            return u"{}".format(result)
 
     def run(self, terms, variables, **kwargs):
 
         ret = []
         for term in terms:
-            '''
+            u'''
             Makes a MongoDB query and returns the output as a valid list of json.
             Timestamps are converted to epoch integers/longs.
 
@@ -206,20 +205,20 @@ class LookupModule(LookupBase):
 -------------------------------------------------------------------------------
             '''
 
-            connection_string = term.get('connection_string', "mongodb://localhost")
-            database = term["database"]
-            collection = term['collection']
-            extra_connection_parameters = term.get('extra_connection_parameters', {})
+            connection_string = term.get(u'connection_string', u"mongodb://localhost")
+            database = term[u"database"]
+            collection = term[u'collection']
+            extra_connection_parameters = term.get(u'extra_connection_parameters', {})
 
-            if "extra_connection_parameters" in term:
-                del term["extra_connection_parameters"]
-            if "connection_string" in term:
-                del term["connection_string"]
-            del term["database"]
-            del term["collection"]
+            if u"extra_connection_parameters" in term:
+                del term[u"extra_connection_parameters"]
+            if u"connection_string" in term:
+                del term[u"connection_string"]
+            del term[u"database"]
+            del term[u"collection"]
 
-            if "sort" in term:
-                term["sort"] = self._fix_sort_parameter(term["sort"])
+            if u"sort" in term:
+                term[u"sort"] = self._fix_sort_parameter(term[u"sort"])
 
             # all other parameters are sent to mongo, so we are future and past proof
 
@@ -232,6 +231,6 @@ class LookupModule(LookupBase):
                     ret.append(result)
 
             except ConnectionFailure as e:
-                raise AnsibleError('unable to connect to database: %s' % str(e))
+                raise AnsibleError(u'unable to connect to database: %s' % str(e))
 
         return ret