split add() to addItem() and add()

differentiates an array of items from a single item

Signed-off-by: Blessing Osakue <iyoworks@gmail.com>
Merge branch 'develop' of https://github.com/iyoworks/DependencySorter
deleted unnecessary file.

Signed-off-by: Blessing Osakue <iyoworks@gmail.com>