Fix code example

$collection is undefined and throws an exception if called as function.
Fix to spelling

Pretty lame, but someone has to do it.
Merge pull request #13 from failpunk/patch-1

Fix code example
Merge pull request #14 from failpunk/patch-2

Fix to spelling
Merge pull request #15 from damrbaby/add-all-sort

Performance optimization: only perform sort once when adding multiple items via addAll
docs(readme): update contributors section
docs(readme): fix url
chore(release): version 0.4.0