Allows DI/1 omitDirectoryAliases to be set to true

By default DI/1 creates two alias for each singleton. For example:

services/User.cfc
Alias One: User
Alias Two: Userservice

You can pass a config option into DI/1 omitDirectoryAliases to omit
alias #2, which is the one Taffy currently favors. This was added in
DI/1 3.0 post-alpha 1.

This code change allows Taffy to continue to favor the #2 allies while
also allowing for cases where #1 alias is the only one available.

May require discussion.