Update README with example of directory creation
Merge pull request #13 from mikeabdullah/patch-1

Update README with example of directory creation
Hold onto referenced data so archive entries can't become invalid
Only once *all* entries from a file are deallocated will the underlying data be deallocated too. Means entries are safe to use as long as you have a reference to them. Reference counting FTW!
Merge branch 'memory-safety' into nsfilewrapper