Description of problem:

The jboss-cli fails to connect when host name contains `underscore` characher.Getting below error message :
~~~
$jboss-cli.sh -c --controller=abc_01:10001
org.jboss.as.cli.CliInitializationException: Failed to connect to the controller
        at org.jboss.as.cli.impl.CliLauncher.initCommandContext(CliLauncher.java:280)
        at org.jboss.as.cli.impl.CliLauncher.main(CliLauncher.java:258)
        at org.jboss.as.cli.CommandLineMain.main(CommandLineMain.java:34)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.jboss.modules.Module.run(Module.java:270)
        at org.jboss.modules.Main.main(Main.java:411)
Caused by: org.jboss.as.cli.CommandLineException: The controller is not available at abc_01:10001
        at org.jboss.as.cli.impl.CommandContextImpl.tryConnection(CommandContextImpl.java:951)
        at org.jboss.as.cli.impl.CommandContextImpl.connectController(CommandContextImpl.java:790)
        at org.jboss.as.cli.impl.CommandContextImpl.connectController(CommandContextImpl.java:766)
        at org.jboss.as.cli.impl.CliLauncher.initCommandContext(CliLauncher.java:278)
        ... 8 more
Caused by: java.io.IOException: java.lang.IllegalArgumentException: destination address may not be null
~~~

- Since underscore is not an valid character in hostname,So we should improve the error message saying the same.

Version-Release number of selected component (if applicable):
NA

How reproducible:

Connect to jboss-cli.sh with hostname containing 'underscore' character.

Steps to Reproduce:
1.$ ./jboss-cli.sh -c --controller=abc_10:9999