Various final backend fixes (#117)

* Various final backend fixes

* Add FS watching

* run lint

* Autodetect installed jars

theseus/library/JavaInfo.java

@@ -0,0 +1,22 @@
+public final class JavaInfo {
+    private static final String[] CHECKED_PROPERTIES = new String[] {
+            "os.arch",
+            "java.version"
+    };
+
+    public static void main(String[] args) {
+        int returnCode = 0;
+
+        for (String key : CHECKED_PROPERTIES) {
+            String property = System.getProperty(key);
+
+            if (property != null) {
+                System.out.println(key + "=" + property);
+            } else {
+                returnCode = 1;
+            }
+        }
+
+        System.exit(returnCode);
+    }
+}