Display chroot names and details

Add option '-a' to operate on all chroots and '-l' to list croutonversion details.
Apologies for just pasting code, but it's difficult to communicate logic simplification via git comments.  Hopefully the following makes sense:

```
        if [ -n "$LISTDETAILS" ]; then
            getversion='y'
            echo "name: $NAME" 2>&1
            if [ -f "$CHROOT/.ecryptfs" ]; then
                if [ ! -d "/var/run/crouton/$CHROOT" \
                        -a "$LISTDETAILS" -gt 1 ]; then
                    sh "$BINDIR/mount-chroot" -c "$CHROOTS" -- "$NAME" || true
                fi
                if [ -d "/var/run/crouton/$CHROOT" ]; then
                    echo "encrypted: yes, unlocked"
                else
                    echo "encrypted: yes, locked"
                    getversion='n'
                fi
            else
                echo "encrypted: no"
            fi
            if [ "$getversion" = 'y' ]; then
                CROUTON_NO_UNMOUNT=1 sh "$BINDIR/enter-chroot" \
                    -c "$CHROOTS" -n "$NAME" -x /usr/local/bin/croutonversion
            fi
        fi
```

Things still to do: the edit-chroot test needs to be updated to test all the functionality here.