added jekyll-pageless-redirects to plugin list
Merge pull request #1486 from nquinlan/patch-1

added jekyll-pageless-redirects to plugin list
Update history to reflect merge of #1486
Clarify that date_to_xmlschama returns an ISO 8601 string

References #1435
Merge pull request #1488 from troyswanson/iso8601

Clarify that date_to_xmlschema returns an ISO 8601 string
Update history to reflect merge of #1488