Force yes when performing apt-get install. Even though we provide
noninteractive, apt still prompts in some situations.
Grep dpkg-query when checking if package is installed. In some cases,
dpkg -l will exit 0 if the package exists, but is not in an installed
state.
This adds SHOESTRAP_BASE to helpers/default, which
allows the cookbook file to be stored separately from
the rest of the shoestrap stuff, making the shoestrap
directory less cluttered. For example:
Old way:
(cd /shoestrap && ./test1.book)
New way (with cookbook moved to subdirectory 'books/'):
(cd /shoestrap && SHOESTRAP_BASE=/shoestrap ./books/test1.book)
