Add build folder to dockerfile when shrinkwrap
Add build folder to dockerfile when shrinkwrap

With this commit I am adding build folder when we use
--shrinkwrap tag

Signed-off-by: Martin Dekov (VMware) <e87dacb504b072be5c99ab4517895d044ab93206@vmware.com>

itscaro/faas-cli,itscaro/faas-cli,itscaro/faas-cli