Ignore Devel::Cover cache
Switch from /usr/lib/xen-tools/ to /usr/share/xen-tools/ to properly adhere FHS
Consistent amount of blank lines in POD
Don't only allow lowercase "b" for "bytes".

Also put some examples in the according error message.
TODO: test for --size constraints

... and its prerequisites
Update xen-tools.conf comments to be more concise and consistent

Thanks Elmar Heeb!
Make some x-c-i commandline options negatable

Update documentation and tests accordingly.

Also add pygrub = 1 as example to xen-tools.conf, now that the effect
can be reversed via commandline options.
Reindent options in POD
Mention http.debian.net as default mirror also in POD
Update debian/changelog
xt-install-image: Don't bail out if only cdebootstrap is installed

There was a duplicated check on debootstrap being installed and only
one has been expanded when cdebootstrap support was added. So
xen-tools bailed out if debootstrap wasn't installed even if it had
been instructed to use cdebootstrap instead.

This also adds support for cdebootstrap-static.

Additionally xt-install-image dispatcher has been extended to hand
array refs of command paths instead of just single command paths.

Thanks to Elmar Heeb for reporting this issue!
Merge branch 'lib-vs-share'