Bump up the golang for compiling the binaries to 1.12.12
This commit also includes some minor changes to Makefile to fix issue in
building the binary files.
Signed-off-by: Daniel Jiang <jiangd@vmware.com>
This commit bumps up the version of Go to compile the code to v1.12.5,
and shifts to go.mod for managing depedency.
Some code from "harbor/tests" to "harbor/src/testing" to avoid depedency
loop of modules.
Note that in short term we will still vendor the dependency.
Signed-off-by: Daniel Jiang <jiangd@vmware.com>
