change mongodb type for roles to be collection instead of hash

Author: MDrollette

Resources/config/doctrine/Group.mongodb.xml

@@ -8,7 +8,7 @@
 
         <field name="name" fieldName="name" type="string" />
 
-        <field name="roles" fieldName="roles" type="hash" />
+        <field name="roles" fieldName="roles" type="collection" />
 
         <indexes>
             <index unique="true" dropDups="true">

Resources/config/doctrine/User.mongodb.xml

@@ -32,7 +32,7 @@
 
         <field name="passwordRequestedAt" fieldName="passwordRequestedAt" type="date" />
 
-        <field name="roles" fieldName="roles" type="hash" />
+        <field name="roles" fieldName="roles" type="collection" />
 
         <indexes>
             <index unique="true" dropDups="true">