Change license copy obtain link from http to https

[kaidohallik]

Changed license copy obtain link in license headers from http://www.apache.org/licenses/LICENSE-2.0 to https://www.apache.org/licenses/LICENSE-2.0 to avoid possible security issues.

This is suggested also in Apache license FAQ: https://www.apache.org/foundation/license-faq.html#Apply-My-Software
And Gradle Wrapper also uses https version of this license link (Maven Wrapper still uses http version).

Made also some polishing in license headers.

• Changed some https://jhipster.github.io/ to https://www.jhipster.tech/
• Changed some http://www.jhipster.tech/ to https://www.jhipster.tech/
• Unified also spacing in licence headers.
• In one .ejs file changed license from code comment to EJS comment.
• Updated some licence headers to the latest version:
  • changed "Copyright 2013-2020 the original author or authors." to "Copyright 2013-2020 the original author or authors from the JHipster project."
  • changed "2013-2018" to "2013-2020"
  • changed "http://www.apache.org/licenses/LICENSE-2.0 = 0" to "https://www.apache.org/licenses/LICENSE-2.0"

FYI: I used document.querySelectorAll('.load-diff-button').forEach(node => node.click()) in Web Console to see all diffs without need to click on them.

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