Date localization issue with .Date.Format

[MirMiz]

Describe the bug
Date localization with .Date.Format doesn't translate e.g. names of Weekdays or Months in diffrent languages well. E.g. if you're trying to use a german datetime format, die Weekdays and Monthnames will stay in english, when using {{ .Date.Format .Site.Params.dateFormat }}

Reproduction steps
set in config.yml

• languageCode: de
• defaultContentLanguage: de
• dateFormat: Mon, 02.01.2006 15:04:05
• shortDateFormat: 02.01. 15:04
  look at die date of an incident in web view -> english names.

Solution
Use {{ dateFormat .Site.Params.dateFormat .Params.date }} instead.
dateFormat is an alias for time.Format (note: time)
it handles timeformats and translations correctly.

• layouts/issues/issue.html uses .Date.Format in line 15. in line 55 & 74 dateFormat is used.
  -> Change line 15 to {{ dateFormat .Site.Params.dateFormat .Params.date }}
• layouts/issues/single.html -> change line 24 to {{ dateFormat .Site.Params.dateFormat .Lastmod }}

[MirMiz]

Additionally:
relative-time on the main page didn't respected the selected dateformat, but defaulted on UTC.
The Title-Attribute (hover) now displays time in the chosen dateformat. an additional Attribut data-date contains the UTC-Format for calculating the relative times using JavaScript. this way the hover shows the date in the selected format