Stores index info with yanked lines.

YankOperations.getYankOperationResult returns an object whose "text"
property is an array of index-content tuples. Previously, it just returned
an array of Strings representing the lines/chars yanked.

var operationResult = YankOperations.getYankOperationResult(args);
console.log(operationResult.text);
// Returns:
// [{ index : 0, content : 'oh' }, { index : 1, content : 'hai' }]
Started implementing DeleteOperations.

Not finished. Simply calls YankOperations.getYankOperationResult with the
same args as is passed to getDeleteOperationResult and logs the response.