allow rodsuser to run a rule string

[d-w-moore]

The command:

irule -r irods_rule_engine_plugin-python-instance python_rule null  null

should succeed if executed by a rodsuser.
In this context, the command line argument python_rule should be taken as the identifier of a python function (a rule) defined in the global namespace of /etc/irods/core.py.
Currently this command only succeeds for a rodsadmin. A rodsuser gets the errorSYS_NO_API_PRIV.

[korydraughn]

The following code is the reason why only rodsadmin users can use irule to invoke rules in core.py.

irods_rule_engine_plugin_python/irods_rule_engine_plugin-python.cxx

Lines 623 to 626 in 0a07fb9

	if ( ( client_user_authflag < REMOTE_PRIV_USER_AUTH ) || ( proxy_user_authflag < REMOTE_PRIV_USER_AUTH ) ) {
	rodsLog( LOG_DEBUG, "Insufficient privileges to run irule in Python rule engine plugin" );
	return ERROR( SYS_NO_API_PRIV, "Insufficient privileges to run irule in Python rule engine plugin" );
	}

If Boost.Python gives us a way to fetch all rules/functions inside of core.py, then we can use that to determine whether the rule text sent by the client should be executed.