Fix #1157 -- include code.css in bundles.

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
bundles should depend on copy_files

If we put assets in FILES_FOLDERS, they should be copied
before we make bundles.

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
Merge pull request #1159 from getnikola/fix-bundles-code-css

Fix #1157 -- include code.css in bundles.