anna-install returns:
0 if a package was installed successfully
0 if anna is not yet configured with a udeb source and the package
installation was queued for later
0 if no package was installed (ie, package already installed)
1 if anna is configured with a udeb source but the requested udeb is not
available there
10 if the Packages file download failed
5 if some memory allocations fail
6 or 7 if a retreiver fails to retreive a package and its internal error
handler also fails to handle the error
8 if the package fails to unpack or configure