[JBIDE-17611] Error when calling Tern code assist via command

Update preferences for Node.js at startup and set first none native as default
Remove duplicated org.eclipse.ui dependency
Added a preference that disables repeatable Node.js config change

Signed-off-by: vrubezhny <vrubezhny@exadel.com>
I don't think we need to have certainly THIS code in Tern.java. IMHO, it should be done in preference initializer, thus, making the Node.js installation that is bundled with Tern.java to be the default one. 
Yet another problem is that is wrong (or non-existing) Node.js installation is selected in proposals, there is only an exception is logged into the console. It's not informative enough. IMHO, we either need to display an error dialogue that will propose a user to change the Node.js preferences, or (and) put some detain error message into the Error Log (instead of that exception).
I'll make a PR with proposal to Tern.java a bit later.