Description
As noticed by Maximilian Hütter in this email thread...
http://www.nabble.com/SOLR-218-problem-to19266169.html#a19266169
...when a person tries to register a QParser (or ValueSourceParser) with the same name as a "standard" implementation it gets blown away by the initialization code for the standard impls.
we need to allow people to override these standard names the same way they can with responseWriters, etc...