Replace Website with github pages

[stephanr]

The following activities have to be done to replace the old website with github pages:
(Aggreated from the TMC meeting https://github.com/deegree/deegree3/wiki/tmc-meeting-minutes-20190329)

• content releated tasks

  • fill or remove the placeholder text
    • use first paragraph of startpage for About this site
  • final enhancements in layout and colour
  • remove rss and atom links (including the backend functions)
  • hide sitemap.xml link in the footer
  • migrating blog entries to wiki or web page
  • add https://gis.stackexchange.com/questions/tagged/deegree
  • add gisoverflow to website links
  • add remark to README.md regaring local development
  • re-enable analytics

• administrative tasks

  • transfern website repository to deegree organisation on github (from http://github.com/stephanr/deegree-website/)
  • Prepare use of deegree.org domain name: https://help.github.com/en/articles/using-a-custom-domain-with-github-pages
  • open an issue in OSGeo SAC trac to change the DNS entry (Trac to OSGeo SAC - https://trac.osgeo.org/osgeo)

• post migration tasks

  • review issue handbook: publish on github.io/deegree3 #482
  • review if analytics are working correctly
  • disable joomla
  • correct dehydrated / letsencrypt list of domains handled on plaza (/etc/dehydrated/domains.txt on plaza)
  • check if the "fork me on github bage" can be restored

After processing this issue, the following issues are no longer relevant:

• Poor Blogging module on deegree website #515
• Preffered Link for github Logo on the Website #493
• Obsolete PHP version website www.deegree.org #831

The previous evaluation was done in Issue #906

[stephanr]

I replaced the master branch on https://github.com/deegree/deegree.github.io with the squashed version of the prepared jekyll based one.

This version is now available at http://deegree.github.io/.

I've also prepared the use of www.deegree.org / deegree.org via the Github page settings, so we can trigger the DNS changes tomorrow if there are no new change requests to the page in the TMC meeting tomorrow.

[stephanr]

To test the website, you must access it via http until the DNS is updated.
It is also necessary to add the following entry to the local hosts file:

# deegree.org testing
185.199.109.153 deegree.github.io www.deegree.org deegree.org

[stephanr]

The required changes would be:

@                        IN CNAME          deegree.github.io.
www                      IN CNAME          deegree.github.io.

[tfr42]

Issue for OSGeo SAC created https://trac.osgeo.org/osgeo/ticket/2272

[stephanr]

The DNS change took place on the weekend, so the website address had to be changed in the configuration to avoid HTTPS warnings.

This was done in commit deegree/deegree.github.io@4b76d0f.

[stephanr]

I reopended the sac issue at https://trac.osgeo.org/osgeo/ticket/2272#comment:5 as it looks like other entries have been changed.

[stephanr]

Due to the dns problems we have decided to continue redirecting from deegree. org to www.deegree.org via plaza. (https://trac.osgeo.org/osgeo/ticket/2272#comment:12)

I also disabled the jommla site on plaza.

[stephanr]

In today's TMC Metting from 24.05. we agreed to continue the still open items as separate issues, accordingly this issue will be closed.