Tele build vendoring of sha256 references (invalid tag format)

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tele build is throwing a weird error

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ERROR REPORT:
Original Error: *docker.Error API error (500): {\"message\":\"invalid tag format\"}

Stack Trace:
	/gopath/src/github.com/gravitational/gravity/lib/app/service/docker.go:218 github.com/gravitational/gravity/lib/app/service.tagImageWithoutRegistry
	/gopath/src/github.com/gravitational/gravity/lib/app/service/vendor.go:272 github.com/gravitational/gravity/lib/app/service.(*vendorer).VendorDir.func1
	/gopath/src/github.com/gravitational/gravity/lib/run/run.go:85 github.com/gravitational/gravity/lib/run.(*Group).Go.func1
	/go/src/runtime/asm_amd64.s:2362 runtime.goexit
User Message:
" tele/main.go:23
[ERROR]: API error (500): {"message":"invalid tag format"}

This issue can be caused by the resources being vendored, containing a sha256 reference instead of a tag. The tele build process doesn’t currently support vendoring of images in this style: quay.io/test@sha256:d237a12aa0cde42b539bcb5efc1118ba5e6ca1351b7493ed52bd574d181c5efd

Github Issue: https://github.com/gravitational/gravity/issues/273