add helper function to find IPs of the node

fairmq/tools/README.md

@@ -0,0 +1,35 @@
+# FairMQ Tools
+
+Contains common tools for use by FairMQ and/or users.
+
+## FairMQ::tools::getHostIPs
+
+Fills a map with the network interfaces and their IP addresses available on the current host.
+
+#### Example usage
+
+```c++
+#include <map>
+#include <string>
+#include <iostream>
+
+#include "FairMQTools.h"
+
+void main()
+{
+    std::map<string,string> IPs;
+
+    FairMQ::tools::getHostIPs(IPs);
+
+    for (std::map<string,string>::iterator it = IPs.begin(); it != IPs.end(); ++it)
+    {
+        std::cout << it->first << ": " << it->second << std::endl;
+    }
+}
+```
+##### Example Output
+```
+eth0: 123.123.1.123
+ib0: 123.123.2.123
+lo: 127.0.0.1
+```