add rubymotion/proc spec, test for java.lang.Runnable functionality

test/test-android/app/rubymotion/proc_spec.rb

@@ -0,0 +1,15 @@
+describe "Procs" do
+  it "are based on com.rubymotion.Proc" do
+    obj = Proc.new {}
+    obj.class.should == Proc
+    obj.class.getName.should == 'com.rubymotion.Proc'
+  end
+
+  it "can be passed to Java methods expecting a java.lang.Runnable" do
+    $proc_runnable_ok = false
+    thr = Java::Lang::Thread.new -> { $proc_runnable_ok = true }
+    thr.start
+    thr.join
+    $proc_runnable_ok.should be_true
+  end
+end