column pinning prototype.
simplified pinning logic
making z-index 5 and standard on selection cells.
binding z-index to pinned state in template
getting pinning working with aggregates.
linking aggCol pinning with Selection checkbox pinning

also not running a digest when adding an agg column.
adding pushpin icons
updating build to 1.9.0
Merge pull request #166 from angular-ui/pinning

adding column pinning v 1.9