add option for disabling a list page's title attribute for a given colum...

The issue is that when adding custom formatting to a field into a list page, the title attribute can turn pretty unsightly as shown in this screenshot:

![title_attribute](https://cloud.githubusercontent.com/assets/614981/3869531/45f0f34e-2095-11e4-9444-5f6eb98e33b3.png)

So I added a config option on a property called 'hide_title_attribute'.  Setting it to true will result in a blank title attribute. 

If the pull request is accepted I'll update the wiki.