OPENDJ-808 (CR-1685) Implement a simple commons REST based HTTP connection handler



Added support for ds-cfg-num-request-handlers in the HTTPConnectionHandler configuration to bring it at par with the LDAPConnectionHandler configuration.



02-config.ldif, HTTPConnectionHandlerConfiguration.xml, HTTPConnectionHandlerCfgDefn.properties:
Added ds-cfg-num-request-handlers.

HTTPConnectionHandler.java:
Set the SelectorRunnersCount in grizzly based on the numRequestHandlers property.

LDAPConnectionHandler.java, ConnectionHandler.java:
Moved getNumRequestHandlers() from LDAPConnectionHandler to ConnectionHandler.