Added support for multi-select, default title, ticks to indicate selection, arrow in menu

Hey Silvio,

I have added support for Multi-select to your plugin, however, as you can imainge it required quite a hefty refactor  - so im not sure how well it will merge, if at all you want to merge it, however, this is what is supported in this fork:

**New Classes**
The class `show-tick` on a `select` element will show a tick icon on the selected  row(s).

The class `show-menu-arrow` on a `select` will add the small top arrow on the drop down menu.

**Attributes**
The attribute `multiple='multiple'` on the `select` will enable multiple selection within the drop down, and enable ticks icons by default.

The attribute `title='My Default test'` on the `select` will set the initial prompt text for the main button if no value has been set yet.

**js Properties**
The property `selectedText` in the JS constructor will set how the selected text is displayed.  Values are:
    1. `value` - will show the selected value, or comma delimited values if multiple select.
    2. `count` - will show 'x of x Selected' if multiple selecte.
    3. `count>n` - will show the 'x of x Selected' text only when more then `n` have actually been selected.  Eg values if the `selectedText` is 'count>2', and the selected values are 'One', and 'Two' then the selected text is 'One,Two'.  Once there are more than 2 selected, it will say something like '3 of 4 Selected' .
```javascript
$(".selectpicker.one").selectpicker({ selectedText:'count' });
$(".selectpicker.two").selectpicker({ selectedText:'count>4' });
```
**js Methods**
The method `val` has been exposed as part of the plugin, which will update the `select` value, and trigger a render of the plugin at the same time (this is because the jquery .val() does not trigger onChange.

```javascript
$(".selectpicker").selectpicker("val", "Two");
```

I also exposed the new `render` method, that allows the dev to still manually modify the `select`, and then call `render` themselves when done:

```javascript
$(".selectpicker").val("Two");
$(".selectpicker").selectpicker("render");
```

**Refactor**
To enable easy updating of the component, and easier branching of logic depending on multi select / single select, I refactored the creation and reload methods into one main method that creates the child Lis, which is called both by the `create` method and the `reload` method now.  

This ment reworking the templates slightly, and adding elements via JQ rather than string replace of the template.

I then created a `render` method that simply updates the state of the LI list based on the state of the `select` element.

**Basic Demo HTML**
You can run this to test it out :

```html
<html>
    <head>
        <script language="javascript" src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
        <script src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/js/bootstrap.min.js"></script>
        <link href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css" rel="stylesheet">

        <script language="javascript" src="bootstrap-select.min.js"></script>
        <link type="text/css" rel="stylesheet" href="bootstrap-select.min.css" />
    
        <script>
            $(document).ready(function() {
           
               $(".selectpicker").not(".count-example").selectpicker();
          
                $(".selectpicker.count-example.default-count").selectpicker( {
                    selectedText:'count' 
                });
           
               $(".selectpicker.count-example").selectpicker( {
                    selectedText:'count>2' 
                });
            });
        </script>
    </head>
    <body>
        <div>
            <b>default</b>
            <select class='selectpicker'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>

        <div>
            <b>With arrow in menu</b>
            <select class='selectpicker show-tick show-menu-arrow'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>

        <div>
            <b>With tick</b>
            <select class='selectpicker show-tick'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>

        <div>
            <b>Multiple</b>
            <select multiple='multiple' class='selectpicker'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>

        <div>
            <b>Default text</b>
            <select multiple='multiple' class='selectpicker' title='Select one or more...'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>

        <div>
            <b>Selected text as count</b>
            <select multiple='multiple' class='selectpicker count-example default-count' title='Select one or more...'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>

        <div>
            <b>Selected text as count above 2</b>
            <select id="test" multiple='multiple' class='selectpicker count-example' title='Select one or more...'>
                <option>One</option>
                <option>Two</option>
                <option>Three</option>
            </select>
        </div>
    </body>
</html>

```