ModuleSearcher: remove validity restriction

In contrast to the visible and enabled checks, verifying that a
command is valid triggers class loading and parameter parsing.

It also hopefully avoids problems like this:
http://forum.imagej.net/t/a-search-bar-for-imagej/6735/12

src/main/java/org/scijava/search/module/ModuleSearcher.java

@@ -152,8 +152,7 @@ public static String location(final ModuleInfo info, final String baseDir) {
 	// -- Helper methods --
 
 	private boolean isGoodModule(final ModuleInfo info) {
-		return info.isValid() && info.isVisible() && info.isEnabled() &&
-			title(info) != null;
+		return info.isVisible() && info.isEnabled() && title(info) != null;
 	}
 
 	private boolean startsWith(final ModuleInfo info, final String desiredLower) {