Added position option to array push & pop

[eliachiarucci]

Added an option for selecting the index position of the push & pop operations.

Example:

{ _id: 'id10', planets: ['Earth', 'Venus', 'Mars'] } Initial Array

db.update({_id: "id10"},  {$push : {planets: "Pluto"}, {position: 2}, function(){}

{ _id: 'id10', planets: ['Earth' , 'Venus' , 'Pluto' , 'Mars'] } Resulting Array

[thw0rted]

No PRs have been merged for well over a year. Is there any reason to think this project isn't abandoned?