feat(choices): allow to set default dropdown position

[dimirc]

We should be able to set dropdown position explicitly so I added a new attribute called position for the <ui-select-choices> tag, that will accept 3 values: up, down and auto

Sometimes we might not want the dropdown to go automatically up even when there isn't enough space, so now we can force position to always go to an specific direction.

Also you can specify globally at uiSelectConfig using dropdownPosition

Demo plunker

[isimonov]

Thanks a lot! My example works correctly http://plnkr.co/edit/Tzcp1q2WV7HZCp5meftC?p=preview

[karptonite]

This is actually not working properly for me.
http://plnkr.co/edit/NuSM3OfJUgbxCRYoln8z?p=preview
The role selector is set to position="down" and the select options go down at first, but then reverses if you type a letter, then delete it.
http://quick.as/wy2mc3zva

[dimirc]

@karptonite I found the bug and will push a new patch release today

[karptonite]

@dimirc Thanks! Your work on this is certainly appreciated!

[dimirc]

@karptonite v0.13.1 released and now your issue should be fixed. Check updated demo http://plnkr.co/edit/H6ZSPuZ6qnEEJAF4dFrA?p=preview