[ADD] Back To Top (B), SINCE: Date

[VerzatileDev]

[ADD]
-- Button --

 An option to scroll back to the top, to avoid doom scrolling manually on longer Content pages.

-- SINCE: Date --

Edit Date now is using a dependency Pluging, captures the editing date of the given file.

Installed in the GemFile, uploaded to gemfile.lock

Plugin is called in config.yml as a plugin and optional Date Format is included
if it might miss on the page " Currently globally declared for each page through "footer.html"

!! Used through Footer.html !! 
 to ask for the given date and specify for each file.

References are listed as the following for this plugin.
#https://github.com/gjtorikian/jekyll-last-modified-at

Currently It is missing the Author, see additional information that might come in handy from the "Report" #40

[JDSherbert]

lgtm