minor bugfix that will catch connection errors in iosxr

This commit fixes a situation where connection errors would be caught
but no useful information display.  The connection error is now caught
and emitted in a call to fail_json

lib/ansible/module_utils/iosxr.py

@@ -49,7 +49,12 @@ class Cli(object):
         password = self.module.params['password']
 
         self.shell = Shell()
-        self.shell.open(host, port=port, username=username, password=password)
+
+        try:
+            self.shell.open(host, port=port, username=username, password=password)
+        except Exception, exc:
+            msg = 'failed to connecto to %s:%s - %s' % (host, port, str(exc))
+            self.module.fail_json(msg=msg)
 
     def send(self, commands):
         return self.shell.send(commands)