Add a Makefile target 'distdocs' that generates the documentation
at 'make dist' time (and does not depend on configure).

This simplifies the makefile dependency structure within the doc/
subdirectories a bit and makes it easier to prevent docs from being
built, by removing the 'dist: distdocs' dependency in the root Makefile.
Copy /etc/hosts to chroot next to resolv.conf for DNS resolution.
Uniformize style and order of displaying file size and md5.
Fix HTML validation errors.
Fix two HTML validation errors.
Use tab indentation, no functional change.
Increase post limits for REST API.
Uniformize Debian and Ubuntu make_chroot scripts.
Update changelog, note that scripts in DB closes #123.