When copying filesets into the build context, file metadata should be preserved

[jakedt]

In order to work around this:
moby/moby#3556

File metadata should be preserved when the build context directory is created. The easiest way to accomplish this would be to add a preserve flag to the fileutils cp and cpr functions, to behave the same as cp -p, and then to utilize the flag when creating the context.

[rafecolton]

Yep, definitely needs to be address, first in go-fileutils

[rafecolton]

Addressed and available in release v0.7.1