Drop IE8 support

[seriema]

It's causing more and more hacks. The biggest change for AngularJS support will be that version 1.2 will be dropped, as they dropped IE8 support in 1.3.

Here's a checklist of things to change in the source once the IE8 support gets dropped:

• [ ] Trailing commas: Change JSCS config from disallowTrailingComma to requireTrailingComma with ignoreSingleLine and ignoreSingleValue.
• [ ] Pollyfills: Remove code with TODO: IE8:
• [ ] SauceLabs: Remove SL_IE_8 from karma.conf.js and Gruntfile.js
• [ ] Angular: Remove 1.2 from Gruntfile.js and update bower.json to ^1.3.0

[seriema]

If we at least could rely on es5-shim being present we could drop a few polyfills. But AngularJS doesn't require it so it might be unbalanced. The biggest gain would be dropping Angular 1.2 support either way.

[seriema]

Microsoft stopped supporting older IE's on the glorious day 12th January 2016. [reference]

I will drop support for IE8 soon. I haven't decided if I'll keep Angular 1.2 support.