version bump 0.2.18: XLSX 0.5.14, XLS 0.6.15
version bump 0.2.19: XLSX 0.5.15, XLS 0.6.16
Merge branch 'master' of github.com:SheetJS/j

* 'master' of github.com:SheetJS/j:
  version bump 0.2.19: XLSX 0.5.15, XLS 0.6.16
  version bump 0.2.18: XLSX 0.5.14, XLS 0.6.15
Providing a length to Buffer.concat() in readFileAsync