Fix sig v4 detection (#77)

Regenerate gemspec for version 0.7.0

Regenerate gemspec for version 0.5.0

Regenerate gemspec for version 0.4.3

Regenerate gemspec for version 0.4.2

Regenerate gemspec for version 0.4.1

Regenerate gemspec for version 0.4.0

Regenerate gemspec for version 0.3.2

Regenerate gemspec for version 0.3.1