Revert "Added System.IO.Compression implementation."

This is currently breaking the build for Mono Droid.

This reverts commit b175675ad9cf513f3ee3772091b3bfd02849213c.
Revert "Added our own slightly modified copy of Ionic.Zip library."

This is currently breaking the build for Mono Droid.

This reverts commit bb3f24e99977a16ee4ce7540dd9c569bbf4575be.