log boot script output to file.

change bootsync.sh to bootscript.sh and output console to /boot.log #366


I'm going to work to finish #366 here.
This whole section looks completely out of place - see lines 41 and 42 above:
```sh
# Make some handy symlinks (so these things are easier to find)
ln -fs /var/lib/boot2docker/docker.log $ROOTFS/var/log/
ln -fs /usr/local/etc/init.d/docker $ROOTFS/etc/init.d/
```