Converts the majority of docs over to use the Markdown language for
pretty printing on GitHub. It's a rough first convertion without
exploiting the full potential of Markdown at this point. Section
titles and indentation are fixed as needed. Minimal docs interlinking
is added.

Signed-off-by: Thomas Graf <tgraf@noironetworks.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

Our Debian and XenServer packages use /etc/openvswitch/conf.db as the
location for the database but some of the docs suggested
/etc/ovs-vswitchd.conf.db.  This settles on the former consistently.
The manpage is still ovs-vswitchd.conf.db but I don't know what to do
about that.

Burying the description of the problem, which is usually the most important
part in my experience, at the bottom of the REPORTING-BUGS file might be
the reason why we don't get good descriptions sometimes.  It is certainly
not the reason in other cases, but we might as well prioritize a bit
better.