[CS AUDIT] Arbitrary Contract are trusted

[branciard]

[CS AUDIT] Arbitrary Contract are trusted

[Amxx]

proposed solution is not enough.

Functions like rewardForWork are under threat of forged workorder.
workorder must be authentic to trigger a reward, and must be removed lose it's flag once inalized to avoid further rewarding

[branciard]

fixed in https://github.com/iExecBlockchainComputing/PoCo/tree/v1.0.13