client: fix marshaling of int64 type

[maksym-nazarenko]

Closes #221

[ddelnano]

Thanks for fixing this @maksym-nazarenko!

[ddelnano]

Hm, the build for the latest RouterOS seems to be failing. Upon looking at it briefly it seems like doesn't seem related to your change, but I wasn't able to dig into it right now.

I did notice that the evilfreelancer/docker-routeros project has automated creating new docker images (EvilFreelancer/docker-routeros#20). I wonder if it's also failing on master and is independent of your change.

Re-requesting review until we uncover what is wrong with the latest build. Feel free to proceed with merging if it isn't something that requires a review (if master is experiencing the same issue but passes locally, etc).

[maksym-nazarenko]

created #224
It is and issue with upstream RouterOS container

[ddelnano]

Thanks for investigating. No concern on my end with proceeding to merge.