Implemented a baseAbsList for ListView and GridView.

Also added a parameter to customize the main layout used.

The defalut list uses [`view_progress_listview`](SuperListviewLibrary/src/main/res/layout/view_progress_listview.xml) layout and the default grid uses the [`view_progress_gridview`](SuperListviewLibrary/src/main/res/layout/view_progress_gridview.xml) layout.

Now you can use your custom layout (pay attention to ids!) using this attrs in your view:
[`superlistview:superlv_mainLayoutID`](SuperListviewLibrary/src/main/res/values/attrs.xml#L24)
Example:

```xml
<com.quentindommerc.superlistview.SuperListview
            xmlns:superlistview="http://schemas.android.com/apk/res-auto"
            android:id="@+id/list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            superlistview:superlv__clipToPadding="false"
            superlistview:superlv__divider="@android:color/transparent"
            superlistview:superlv__dividerHeight="10dp"
            superlistview:superlv__Padding="10dp"
            superlistview:superlv__empty="@layout/emptyview"
            superlistview:superlv__scrollbarStyle="outsideOverlay"
            superlistview:superlv_mainLayoutID="@layout/custom_view_progress_listview"
        >
```