Build: Remove grub from default build process

This removes grub and all the loopback device business from the default
build process. Running grub takes about a second, and it turns out it's
inconsistently packaged in different distributions, which has led to
at least one confusing issue so far (grub-install vs grub2-install).
Removing it from the basic path will make it easier for people to try
Serenity out.

There are now two scripts that can be used to build a disk image:

1. `build-image-grub.sh` - this will build an image suitable for writing
   to the IDE hard drive of a physical machine, complete with a partition
   table and bootloader. This can be run in qemu with the `qgrub` target
   for the `run` script.
2. `build-image-qemu.sh` - this is a simpler script which creates a bare
   filesystem image rather than a full MBR disk.

Both of these call out to `build-root-filesystem.sh` to do most of the
work setting up... the root filesystem.

For completeness' sake, I've retained the `sync.sh` script as a simple
forwarding to `build-image-qemu.sh`.

This relies on the functionality from #194 and #195. #195 allows us to
use `/dev/hda` as the root device when nothing else is specified, and #194
works around a strange feature of qemu that appends a space to the kernel
command line.

Kernel/run

@@ -18,6 +18,7 @@ elif [ "$1" = "qn" ]; then
         -device VGA,vgamem_mb=64 \
         -debugcon stdio \
         -device e1000 \
+        -kernel kernel \
         -hda _disk_image \
         -soundhw pcspk
 elif [ "$1" = "qtap" ]; then
@@ -30,6 +31,19 @@ elif [ "$1" = "qtap" ]; then
         -object filter-dump,id=hue,netdev=br0,file=e1000.pcap \
         -netdev tap,ifname=tap0,id=br0 \
         -device e1000,netdev=br0 \
+        -kernel kernel \
+        -hda _disk_image \
+        -soundhw pcspk
+elif [ "$1" = "qgrub" ]; then
+    # ./run qgrub: qemu with grub
+    $SERENITY_QEMU_BIN -s -m $ram_size \
+        $SERENITY_EXTRA_QEMU_ARGS \
+        -d cpu_reset,guest_errors \
+        -device VGA,vgamem_mb=64 \
+        -debugcon stdio \
+        -object filter-dump,id=hue,netdev=breh,file=e1000.pcap \
+        -netdev user,id=breh,hostfwd=tcp:127.0.0.1:8888-192.168.5.2:8888 \
+        -device e1000,netdev=breh \
         -hda _disk_image \
         -soundhw pcspk
 else
@@ -42,6 +56,7 @@ else
         -object filter-dump,id=hue,netdev=breh,file=e1000.pcap \
         -netdev user,id=breh,hostfwd=tcp:127.0.0.1:8888-192.168.5.2:8888 \
         -device e1000,netdev=breh \
+        -kernel kernel \
         -hda _disk_image \
         -soundhw pcspk
 fi