found unused vars etc in ./common/...

honnef.co/go/tools/cmd/unused found unused vars etc in ./common/...
common/cauthdsl/cauthdsl_test.go:96:6: func NewMockDeserializer is unused (U1000)
common/config/standardvalues_test.go:47:2: field msg is unused (U1000)
common/errors/errors.go:33:2: var errorLogger is unused (U1000)
common/genesis/genesis.go:30:2: const lastModified is unused (U1000)
common/ledger/blkstorage/fsblkstorage/blockfile_mgr.go:45:6: type conf is unused (U1000)