sc-build --target option does not include images

[krotscheck]

We discovered a bug with sc-build while trying to target a different directory- it doesn't appear to package any of the theme images. Here's a repro:

Preconditions:

• sc-init sc-build-test
• cd sc_build_test/

  Expected Behavior:

• sc-build
• find ./tmp/* | grep png

Lots of images found. Output is at ./tmp/build/static/*

Unexpected behavior

• sc-build --target=./foo
• find ./foo/* | grep png

Note no images found. Output is at ./foo/static/*

[juanpin]

Try using --build_targets target should probably be deprecated