Parse ‘isDefault’ and ‘isMandatory’ from remote bundle index
Only report failure from updating a source when there is no cache

Ideally we would also return ‘false’ when failing to update an existing source, but not failing when we have a cache is better than failing when there is nothing new to download.
Update ‘bl’ to support list/install of default/mandatory bundles

We now have four meta-names: outdated, installed, defaults, and mandatories. These can be used to list or update/install the respective group of bundles.
Create archive of default bundles by using the server side status
Add ‘sysexits.h’ as a precompiled header
Use constants from sysexits.h for bl failure codes
Use more constants from sysexits.h for pretty_plist failure codes