Add collection and table view sugars

[zenangst]

This PR adds some sugars for inserting, updating and deleting indexes on a UITableView or UICollectionView.

public extension UICollectionView {
  func insert(indexes: [Int], section: Int = 0, completion: (() -> Void)? = nil) {}
  func reload(indexes: [Int], section: Int = 0, completion: (() -> Void)? = nil) {}
  func remove(indexes: [Int], section: Int = 0, completion: (() -> Void)? = nil) {}
  func reloadSection(index: Int = 0, completion: (() -> Void)? = nil) {}
}

public extension UITableView {

  func insert(indexes: [Int], section: Int = 0, animation: UITableViewRowAnimation = .None) {}
  func reload(indexes: [Int], section: Int = 0, animation: UITableViewRowAnimation = .None) {}
  func remove(indexes: [Int], section: Int = 0, animation: UITableViewRowAnimation = .None) {}
  func reloadSection(section: Int = 0, animation: UITableViewRowAnimation = .None) {}
  private func performUpdates(@noescape closure: () -> Void) {}
}

If you only have one section and no completion you could just run;

tableView.insert([1,2,3])

[vadymmarkov]

@zenangst Nice!