Cleans up HTML data attributes on body in default.hbs

closes #4485

- removes data attributes used on body in default.hbs
- introduces new way to generate configuration through meta tags
- config initializer consumes configurations from the meta tags using parser
- moves blog_title helper/value to be a property in a configuration api
Merge pull request #4531 from Gargol/issue-4485

Cleans up HTML data attributes on body in default.hbs