Update references to GitHub repository and issues

With the migration of the RAP Git repository from Gerrit to GitHub, and
the ticketing system from Bugzilla to GitHub issues, all the references
in the web page must be updated to the new URLs.

Bug: https://github.com/eclipse-rap/org.eclipse.rap/issues/1
Change-Id: Ifc42d95d02eaa2ccf5fea340e90a609c45cb229f
Signed-off-by: Markus Knauer <mknauer@eclipsesource.com>
8 files changed