added clickToSelect to columns

I tried to use both clickToSelect and column events to trigger click events for links and buttons but the checkbox click event triggered also.  I thought it good if we could control which columns would trigger the row selection so the two click events don't always get triggered.

I tried to keep the attributes the same so the attribute for enabling/disabling the column is also clickToSelect and it defaults to true so as to be backward compatible.

```
<table data-url="data1.json" data-height="299" data-click-to-select="true" data-search="true">
    <thead>
        <tr>
            <th data-field="state" data-checkbox="true"></th>
            <th data-field="id" data-align="right">Item ID</th>
            <th data-field="name" data-align="center">Item Name</th>
            <th data-field="price" data-align="">Item Price</th>
        	<th data-field="operate" data-formatter="operateFormatter" data-events="operateEvents" data-click-to-select="false">Item Operate</th>
        </tr>
    </thead>
</table>
<script>
    function operateFormatter(value, row, index) {
        return [
            '<a class="like" href="javascript:void(0)" title="Like">',
                '<i class="glyphicon glyphicon-heart"></i>',
            '</a>',
            '<a class="edit ml10" href="javascript:void(0)" title="Edit">',
                '<i class="glyphicon glyphicon-edit"></i>',
            '</a>',
            '<a class="remove ml10" href="javascript:void(0)" title="Remove">',
                '<i class="glyphicon glyphicon-remove"></i>',
            '</a>'
        ].join('');
    }

    window.operateEvents = {
        'click .like': function (e, value, row, index) {
            alert('You click like icon, row: ' + JSON.stringify(row));
            console.log(value, row, index);
        },
        'click .edit': function (e, value, row, index) {
            alert('You click edit icon, row: ' + JSON.stringify(row));
            console.log(value, row, index);
        },
        'click .remove': function (e, value, row, index) {
            alert('You click remove icon, row: ' + JSON.stringify(row));
            console.log(value, row, index);
        }
    };
</script>
```