Change name of SHA1 files: 'foo.sha1' now contains SHA1 of file 'foo'
Drop the backup bootloader, and redirect 'dd' output to stderr
Use variables instead of hard-coding paths everywhere
Copy the kernel and root filesystem before checking the SHA1
Calculate the SHA1 of the copied files, not of the ones in the OPK
Copy SHA1 files along with the kernel and the rootfs
Update .gitignore to ignore the bootloader files as well