Change to ZIP/XML import logic

Fixes bug #28. We no longer check the MIME type of ZIP content
and instead try to expand it and succeed if a valid ZIP entry is
found. Some changes have been made to the API to accommodate this
safely.
Fixed inappropriate use of RedirectAttributes
Refactored IoUtilities down to nothing

* Some methods moved to ServiceUtilities, and now throw
QtiworksRuntimeException if things go wrong
* Other methods replaced with analogues in Apache commons-io