fixes enable_extension bug in postgresql_adapter

The use of quotations is required to install extensions with certain
characters in them (e.g. uuid-ossp).

removes CHANGELOG entry

Deemed unnecessary.

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -594,7 +594,7 @@ def supports_ranges?
       end
 
       def enable_extension(name)
-        exec_query("CREATE EXTENSION IF NOT EXISTS #{name}").tap {
+        exec_query("CREATE EXTENSION IF NOT EXISTS \"#{name}\"").tap {
           reload_type_map
         }
       end