Set rpm macro information in anaconda-yum.

yumpayload.py uses rpm.addMacro to set rpm macro values, which does
exactly nothing because anaconda-yum runs in a separate process with a
different transaction context. Surprise!

Also, these settings should be shared by every packaging class that uses
rpm, not just used by yum.  Add a rpmMacros property to PackagePayload,
move the macro settings into PackagePayload.preInstall, and modify the
call to anaconda-yum to include the rpmMacros values in --macro
arguments.

(cherry picked from commit 9d0ae8841cb6fd6840f9c2495723cbca5e2b4fc1)
Implement %packages --instLangs (#156477)

(cherry picked from commit a5beb04d9dd0d521fc89a76023bf3d996b253329)
Provide ways in kickstart to skip kernel and bootloader (#1074522).

This patch (along with those in pykickstart and blivet) allows for a kickstart
file to do the following:

(1) Prevent any kernel package from being installed by putting "-kernel" in the
%packages section.

(2) Prevent any bootloader package from being installed (and therefore, any
bootloader config from being written) by putting "bootloader --disabled" in
the command section.

(cherry picked from commit 036f68a1cbd64a21b76b0a368b9f991a25b33da3)