fix: Incorrect file copied message (#37)

[miguelmoraperea]

When copying a file outside the original directory (cwd) the file is not
copied, this is expected, but the user still gets the following message:

[file] has been copied!

This is incorrect, this commit fixes the issue by verifying the result
status from the copy operation and prints the appropriate message
'[file] has been copied!' or '[file] has not been copied' depending on
whether the operation succeeded or not.

[fdschmidt93]

Thanks for your PR :) Irrespective of the discussion on the original issue, this seems like a good change.

I'll try to test drive it and look into it soon.

[miguelmoraperea]

I might've moved some branches in my forked repo, and it seems this PR got closed automatically, anyways I opened a new one:
#45

:)