OTContract: replace OTCleanup with std::unique_ptr
OTASCIIArmor: replace OTCleanup with std::unique_ptr
OTCachedKey: replace OTCleanup with std::unique_ptr
Merge pull request #115 from lclc/otcleanup2

OTContract, OTASCIIArmor, OTCachedKey: replace OTCleanup with std::unique_ptr