documentation: Preparation for 1.9 builds

documentation: Preparation for 1.9 builds

This involves the following:

 * Inserting a new row for all manual revision history tables
   to have "October 2015" and 1.9 as the release information.

 * Updating the mega-manual.sed file to process links for 1.9

 * Updating variables in poky.ent to deal with the 1.9 release
   variables.

(From yocto-docs rev: 1ed55c08b96cf0fded38833635111a5c6da86781)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>