Add a trigger for creating/updating the initramfs.

It's activated at post-install time, and only if template uses:
triggers="initramfs-tools". Use it in the kernel package.

Also print a message when a trigger is being run.

--HG--
extra : convert_revision : 3f2a0c113ed523e4b09822665cf6d94e30b7d1e4

templates/kernel/template

@@ -17,6 +17,8 @@ long_desc="
  This package provides the linux kernel image, kernel modules
  and firmware files."
 
+triggers="initramfs-tools"
+
 Add_dependency full glibc
 Add_dependency full dash
 Add_dependency full coreutils