Update spec to be valid with rspec 3.0
Correctly format timestamps of static files.

Use %S for seconds of the minute instead of %s for seconds since the
UNIX epoch
Lock rspec dependency at ~> 3.0
Merge pull request #24 from Hypernova-Design/bug-fixes
Update history to reflect merge of #24 [ci skip]
added an issue and solution.
Merge pull request #28 from davidsilvasmith/patch-1

added an issue and solution to the readme
Bring the spec into the 21st century
Update version to 0.5.0
Make sure no layout is used for sitemap.xml
Add explicit data['layout'] = nil to halt Jekyll build warning.

Closes #31.
Merge pull request #32 from jekyll/null-layout
Update history to reflect merge of #32 [ci skip]
Release :gem: v0.5.1