Fix styles on IE

[marco-gallinari]

As per angularjs guidelines, style binding is not working on IE. Template needs binding on ng-style to make this work properly.

Trying to figure out a solution on my own.

I think the main problem should be merging cell, row and columns styles; this could be done in ng-style by binding to a function, but rendering performance would suffer a lot.

What I'm trying to do is creating a new version calculating ng-style objects inside $$getCellData function.