[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>
@Override
	public void save() throws IOException {
		try {
			getStorePreferences().flush();
			dirty = false;
		} catch (BackingStoreException e) {
			throw new IOException(e.getMessage());
		}
	}


So, flush is done inside save() method. No need to duplicate that call.