Exposing a data attribute

Exposing data attribute as I find it a little more natural to use than the loadData function callback (left that exposed to prevent any breaking changes)
Column Click Events & Minimum Viewable Area

1) Adding on-column-click event which includes the start and end date on the event (so you can create a new event for the specified "cell"). This required adding endDate to all columns. Also created column class for consistency
2) Adding fromDate and endDate attributes to specify the minimum size of the chart. Previously if it no tasks the gantt was not visible. At this point this does not cut off events past the from or the to just ensures that the from and to dates are visible
Updating docs
Removed duplicated foreground section from HTML template
Bug fix to clear data properly when setting data

Also adding a field for "data" allowing additional data to be added to the row. Long term this should probably be refactored to allow your own Row/Task classes
Removing generated columns

Switching to a  method of efficiently calculating the date clicked without generating divs for each column*row.
Expose view-scale-factor

Allowing you to do things like have days larger than hours
Updating docs
Allowing gantt directives to be used as an attribute which is the only way to get it to work in IE < 9

This requires changes to the template which I'm not providing here but just replace all directives to a div and add the proper attribute
Fixing formatting
Merge branch 'master' of https://github.com/iOffice/angular-gantt into feature/pull-request-4
Adjusted formatting and added missing columns which got removed because of the merge
Bugfix: Added data property to row clone and copy
Remove onColumnClicked (use onRowClicked instead)
Added the 'data' property to the demo
Added a custom data property to the tasks
Merge branch 'feature/pull-request-4' into develop