Make default store inventory automatically if it doesn't exist

[VoxSecundus]

At the moment, trying to import new inventory information results in the command line spitting out:

Importing data.zip
inventory: Directory /home/root/flight-inventory/var/default not found.
Please create it before continuing.

While it's very easy to just mkdir the default directory, it may be useful to just create that directory if it doesn't exist automatically.

[benarmston]

This has been fixed in f2e42ca.