paket restore cache layout changed

[Larusso]

Description

The paketRestore UP-TO-DATE check is broken due to a change in the latest paket versions (The version is unknown because this issue just popped up). The content of the restore cache file used to be a copy of the lock file. The content is now a json payload with multiple hashes.

Steps to reproduce

1. install dependencies with paketInstall to create a paket.lock file.
2. delete the packages directory
3. run the task paketRestore to restore the packages directory
4. run the task paketRestore again

Expected behavior

The task should be UP-TO-DATE

Actual Behavior

The task is not UP-TO-DATE