Clean more from ironic-agent ramdisk image

While we already clean a number of things off the ironic-agent
ramdisk, there are a few more significant ones that we should add
to the list.

First is the kernel source.  If you're rebuilding your kernel on
the agent ramdisk after the initial image build, then you need to
re-examine your life choices. ;-)

Second is /var/cache.  On yum-based distros, this contains a large
number of yum cache files that take up significant space.  We don't
really want to be copying around caches when booting a ramdisk
anyway, so cleaning this is the right thing to do regardless.

Third is all *.pyc or *.pyo files.  There are a lot of these, so
they eat up significant space and bloat the number of files in the
ramdisk, which makes it take longer to build.  the only purpose for
the files is to slightly speed up Python app startup, and we
probably lose more time transferring the files over the network
than we would gain in quicker start times.  Note that we were
already trying to remove these, but for some reason I was still
seeing them show up in my final images.  It makes more sense to
put them in the same pruning command as all the others anyway.

Fourth is /usr/include.  These are files only needed for
compilation.  See above for my thoughts on compiling in a ramdisk.

These changes have reduced the agent ramdisk from 391 MB to 333 MB
in my local centos 7 builds, and have reduced the number of files
in the ramdisk by over 18000.

Change-Id: I550f9904b9afd12d48da9ba24559acb23133d076

elements/ironic-agent/cleanup.d/99-ramdisk-create

@@ -20,9 +20,6 @@ echo "#disabled" > ./tmp/fstab.new
 sudo mv ./tmp/fstab.new ./etc/fstab
 sudo ln -s ./sbin/init ./
 
-# Remove python object files, they're not particularly useful for a ramdisk
-sudo find ./usr -name "*.pyc" -or -name "*.pyo" -delete
-
 # Note: The pci.ids, which is used by lshw, locate on Ubuntu
 # in /usr/share/misc. Therefore we are removing only the
 # ./usr/share/misc/m* (will remove the magic and magic.mgc files).
@@ -32,12 +29,17 @@ sudo find . -xdev \
     -path './tmp/*' -prune -o \
     -path './boot/*' -prune -o \
     -path './root/.cache' -prune -o \
+    -path './usr/include/*' -prune -o \
     -path './usr/lib/locale/*' -prune -o \
     -path './usr/share/doc/*' -prune -o \
     -path './usr/share/man/*' -prune -o \
     -path './usr/share/info/*' -prune -o \
     -path './usr/share/licenses/*' -prune -o \
     -path './usr/share/misc/m*' -prune -o \
+    -path './usr/src/kernels/*' -prune -o \
+    -path './var/cache/*' -prune -o \
+    -name '*.pyc' -prune -o \
+    -name '*.pyo' -prune -o \
     -print | sudo cpio -o -H newc | gzip > ${IMAGE_PATH}.initramfs
 
 select_boot_kernel_initrd $TARGET_ROOT