Use Logging Services common pages

[vy]

I have revamped the Download, Support, and Security pages of Logging Services (LS) such that they now cover all LS projects. In the Log4j website, I have wired all associated links to there and I have replaced all overlapping content to point to there. Would you consider implementing the following changes for the left menu of the Log4net website?

1. Point "Download" to the LS Download page
2. Remove the "Security Reports"
3. Point the "Security" in the left menu to the LS Security page
4. Replace "Mailing Lists", "Issue Tracking" links with a "Support" link pointing to the LS Support page

[LaurentDardenne]

Does this page ( https://downloads.apache.org/logging/log4net/) need to be updated?

[FreeAndNil]

@LaurentDardenne you are right.
@vy Can you please remove https://dist.apache.org/repos/dist/release/logging/log4net/README.html ?

[FreeAndNil]

@vy I've created #145, please review.

[vy]

@FreeAndNil @LaurentDardenne Removed README.html and KEYS symlink from the https://dist.apache.org/repos/dist/dev/logging/log4net Subversion folder.

https://archive.apache.org/dist/logging/log4net is a (bandwidth-throttled!) HTTP mirror of the Subversion folder (for ASF's legal archiving purposes) and https://downloads.apache.org/logging/log4net is a download-friendly subset of the former containing only the most recent releases.