Validate remote server dir before start/stop/deploy operations

Max said this on irc today:

strykerawb: i got some really weird behavior 12:56:27
maxandersen strykerawb: see this video: http://screencast.com/t/uSDT1EoS 12:56:31
jbossbot Title: 014-07-15_1255 - max.rydahl.andersen's library 12:56:31
maxandersen what is it doing? 12:56:34
maxandersen this is me dragging a project to wildfly server 12:56:42
maxandersen ah the server is configured as remote with blank remote server home... 12:57:05
maxandersen seems that result in complete funky endless loop..

The problem is that he had an empty dir set up on a remote server. So when he tried to publish, this resulted in some unexpected behavior (endless copy progress in this case).

Currently, when you create a remote server, the dialog will not let you leave the server home dir empty. But that is not enough. You can still change it in the server editor to be empty. Rob says he wants to remove this field from the server editor and only use the wizard, but that is still not enough - the user can remote the folder on the remote system at a later time.

We probably don't need to check the folder every time we use it, but at least at the start of each operation such as start/stop server, publish to server.

Also, the New server dialog checks for empty string, but I'm not 100 % sure if it actually checks that the folder exists.