Re-enable ActiveRecord lock! functionality

[alexagranov]

lock just delegates to lock! so adding a spec showing that ActiveRecord::Locking::Pessimistic#lock! is broken.

The problem is in the reimplementation of reload which calls lock but this returns a Relation not the ActiveRecord class so the overridden find(*args) that can handle {no_obfuscated_id: true} never gets called.

I went with just removing the options hash from the call to Relation#find as it doesn't appear it would be used while locking anyway.

[alexagranov]

@namick CI is failing due to broken 1.9.3 build