Refactor message! and storage_value!

[vldm]

1. message! and storage_value! share same code to generate packed like structures, so we need to
   take out shared code to some module.
2. message! and storage_value! has borrowed fields, so we cant derive deserialize for it
3. message! should semantically depend from service
4. there many boilerplate code that user need to write const MESSAGE_TYPE, const SIZE, const SERVICE_ID, and [from => to] to each field

For first iteration we decided:

• Make seperate traits that implements exonum json Deserialize and Serialize aspects (partial implemented in Implement Serialize/Deserialize #71 )
• Implement Field for array of Field (fix Exonum do not support big-endian architectures #32)
• The main idea is code should be well documented, so we should not use associated types for return values.

[dj8yfo]

#[$attr:meta] , #[$attr]

storage_value! (
    D#[doc="struct_description"]
struct ConfigReference {
        const SIZE = 40;
        D#[doc="it's actual from from Config reference"]
        F actual_from: u64    [00 => 08]
        F cfg_hash:    &Hash  [08 => 40]
    }
);

[dj8yfo]

@vldm can you please update the main subtasks you outlined for implementation with @defuz in task description (if there are some changes from what is currently in the header) and also create a separate task with points from second part - post 0.1 release?

[vldm]

@gisochre I decided not split this task, but keep it as tracking.