Add Circular Progress Bar library

/cc @amitbharadwaj @josemontesdeoca 

How to use it:

- XML:

```
   <com.lylc.widget.circularprogressbar.example.CircularProgressBar
        android:id="@+id/circularprogressbar1"
        style="@style/Widget.ProgressBar.Holo.CircularProgressBar"
        android:layout_width="120dip"
        android:layout_height="120dip"
        android:layout_marginTop="10dip"
        circular:backgroundColor="@color/lightgray"
        circular:progressColor="@color/app_green"
        circular:titleColor="@color/black"
        circular:subtitleColor="@color/darkgray"
        circular:strokeWidthCircular="10" />
```

- Code:

```
       CircularProgressBar c3 = (CircularProgressBar) v.findViewById(R.id.circularprogressbar1);
        c3.setTitle("$1200");
        c3.setSubTitle("$600 CONTRIBUTED THIS MONTH");
        c3.setProgress(42);
```