OPENDJ-808 Implement a simple commons REST based HTTP connection handler

Added support for using the Rest2LDAP servlet from OpenDJ HTTPConnectionHandler.



HTTPConnectionHandler.java:
Added support for using the Rest2LDAP servlet + removed the FakeServlet.
Added the JSON_MAPPER constant to parse the JSON config file for Rest2LDAP.
Added getClientConnectionsMap() getter.
Added getConnectionFactory() method, heavily inspired from org.forgerock.opendj.rest2ldap.servlet.Rest2LDAPConnectionFactoryProvider.getConnectionFactory().
In startHttpServer(), silenced Grizzly logging + set the IOThreadStrategy to be single threaded + changed the access path to the servlet.

CollectClientConnectionsFilter.java:
Added support for using the Rest2LDAP servlet.
Removed clientConnections instance member, now get this value from the HTTPConnectionHandler.

config.ldif, 02-config.ldif, HTTPConnectionHandlerConfiguration.xml, HTTPConnectionHandlerCfgDefn.properties:
Added ds-cfg-config-file property to ds-cfg-http-connection-handler objectClass.

http-config.json: ADDED (copied from opendj-rest2ldap-servlet project)


ivy.xml:
Added dependencies to Rest2LDAP.

ivysettings.xml:
Added support for updating SNAPSHOTS.