JBIDE-18267 - ensure agent does not attach to newly detected jvms until ...

...user connects to it in jmx view
The interface doesn't say it, but it's really not for external implementation (as far as I can tell).  A grep on fuseide's source tree shows they import the interface, and use it, but no class in fuseide implements it. 

Technically, yes, this is an API break. But I saw no other solution other than adding an interface method I tried three other workarounds, but short of having jvmmonitor cast to internal IHost implementations (which is a bad idea), nothing else would have worked.