Add minimal support for ipmitool

Adding just a couple of ipmi commands that ipmitool always calls.
I'm doing this because in order to run the ipmitool lan 1 <parms>
instead of just the raw command the get channel info was needed.
diff --git a/groupext.C b/groupext.C
new file mode 100644
index 0000000..b834f9b
--- /dev/null
+++ b/groupext.C
@@ -0,0 +1,31 @@
+#include "ipmid-api.h"
+#include "ipmid.H"
+#include <stdio.h>
+#include <stdint.h>
+
+#define GRPEXT_GET_GROUP_CMD 0
+void register_netfn_groupext_functions() __attribute__((constructor));
+
+ipmi_ret_t ipmi_groupext(ipmi_netfn_t netfn, ipmi_cmd_t cmd,
+                             ipmi_request_t request, ipmi_response_t response,
+                             ipmi_data_len_t data_len, ipmi_context_t context)
+{
+	// Generic return from IPMI commands.
+    ipmi_ret_t rc = IPMI_CC_OK;
+    uint8_t *p = (uint8_t*) response;
+
+    printf("IPMI GROUP EXTENTIONS\n");
+
+    *data_len = 1;
+    *p = 0;
+
+    return rc;
+}
+
+void register_netfn_groupext_functions()
+{
+    printf("Registering NetFn:[0x%X], Cmd:[0x%X]\n",NETFUN_GRPEXT, GRPEXT_GET_GROUP_CMD);
+    ipmi_register_callback(NETFUN_GRPEXT, GRPEXT_GET_GROUP_CMD, NULL, ipmi_groupext);
+
+    return;
+}