Improper validation message is displayed while adding existing name in User manage Viewing access Level.patch for #4727

Improper validation message is displayed while adding existing name in User manage Viewing access Level.

#### Steps to reproduce the issue
1.Go to User Manager: Add New Viewing Access Level
2. Enter public in name field(existing name)
3. Click save button verify the result
4. Following error is displayed.
```
 Error
  Save failed with the following error: Duplicate entry 
'Public' for key 'idx_assetgroup_title_lookup' SQL=INSERT INTO 
`b12lm_viewlevels`
(`id`,`title`,`rules`) VALUES 
('0','Public','[]')
```


#### Expected result
Proper validation message should display.


#### Actual result
Validation message with sql query is displayed.![screen shot 2014-10-17 at 02 03 02](http://issues.joomla.org/uploads/1/c05f95fe3823901230d42fc5baae25a0.jpg)


#### System information (as much as possible)

PHP Built On Windows NT 6.2 build 9200
Database Version 	5.6.12-log
Database Collation 	utf8_general_ci
PHP Version 	5.4.12
Web Server 	Apache/2.4.4 (Win64) PHP/5.4.12
WebServer to PHP Interface apache2handler
Joomla! Version Joomla! 3.3.7-dev Development [ Ember ] 01-October-2014 02:00 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 6.1; rv:32.0) Gecko/20100101 Firefox/32.0 

#### Additional comments