Remove invalid uppercase characters in data-cover attributes

According to the W3 spec, uppercase characters are only valid if they are
preceded by a hyphen.

Browsers automatically lowercases these invalid characters so these
properties were never found before when Blanket initializes.
fix windows node path determine method
Merge pull request #386 from naganowl/development

Remove invalid uppercase characters in data-cover attributes
Merge pull request #411 from hefangshi/fix-windows-node-path

fix windows node path determine method
Merge remote-tracking branch 'upstream/development' into development