scripts in /etc/lbu/pre-package.d/ will be executed prior creating the
tar ball and scripts in /etc/lbu/post-package.d/ will be executed after.

if pre-scripts fails, then will package not be created.

ref #220

try avoid ending up with a lbu media without any apkovl.

fixes http://redmine.alpinelinux.org/issues/show/94

fix bug when there are no backups

trap signals and cleanup.
initial lbu revert.

dont override with default encryption if ENCRYPTION is set in lbu.conf. fixed typo in help text. Thanks to Alexander Poslavsky

release 0.8_beta2. fixed bug update-conf and lbu commit whern there already exist a /etc/lbu/include file