- fixes #571 h/t @FredrikL @mooyoul
- pin npm version in travis, see https://github.com/npm/npm/issues/15855
- updated CFB (fixes #569 h/t @e12009)
- remove BOM for some SpreadsheetML files

case insensitive zip file search fixes:
- fixes #439 h/t @chikh
- fixes #440 h/t @chikh
- fixes #567 h/t @duzun