Developers require easy access to home directory

Developers often want to access home directories easily. The sandbox is actually too good.

It's not mounted by default so the user doesn't put their home directory at risk without their knowledge. This is not a trivial concern. E.g. running an older version of Epiphany after running a newer bst-built version using the same homedir can certainly cause issues.

A per-project project.conf should be able to change the default, but perhaps we should make it easier for developers to decide what they want on a case-by-case basis.