Add ia-hash-table

[deadtrickster]

Indifferent access hash-tables.
Naive port of http://api.rubyonrails.org/classes/ActiveSupport/HashWithIndifferentAccess.html

SOURCE: https://github.com/deadtrickster/ia-hash-table

[quicklisp]

Please add :author info to the system file.

[deadtrickster]

Done