Remove storageReader and move logic to stateManager

[s1na]

StorageReader had been introduced to cache original storage values for EIP-1283, but I find that the logic can be easily implemented within StateManager and there's no need to define a new class and pass it along to many methods and classes.

This affects the logic for the Constantinople hardfork, and as CI only runs blockchain tests for Petersburg, I ran those tests for Constantinople locally and they pass.

[coveralls]

Coverage decreased (-0.1%) to 94.992% when pulling 028e1ee on rm-storage-reader into 3e9a91f on master.

[holgerd77]

Very very much in favor of this change, simplifies a lot, good that you spotted that.

Looks good.