make customizer compilation code more generic. have customizer output Bootstrap Theme too; fixes 12003

BS3 commits: 07309edce54e72dd8cf8441b702a1c8c4eceff2e,
c635d8f5474b5a84114f61161f86dc3d814d8d72
grunt dist build-customizer

BS3 commits: ef7bf0abf8a8ecb6b19bb14cd2d38cb87373f6ba
adjust filename to indicate that customize JS is minified

BS3 commits: c891be5e5f9bfba83e7e8ac6cd42150271eba626
enable CSSLint in test suite; fixes 12094

BS3 commits: a712abd06e76ff353c564f03125eaad8af4b2e74
bump grunt-contrib-less to v0.9.0

BS3 commits: 9ae5d321b5b35388b7b734275963f7575b4fcc79
no preboot

BS3 commits: 692eb554aa3409f6f74de1605e1925ee295f4571
grunt