Add IMPORT_FILE_PATH and MISSING_FILE_LOG to dev box env

[ksclarke]

To be able to import images we need two variables set in the dev box's env setup. This will go in the Ansible roles for capdeploy:

https://github.com/UCLALibrary/uclalib_role_samvera_capdeploy/blob/master/tasks/dotenv_setup.yml

(in the template file)

Acceptance:

• The environment files have been updated in the related role
• The example.csv spec fixture can be imported with images that display in the UI

[ksclarke]

And make it clear in some VM dev box documentation that the IMPORT_FILE_PATH variable needs to be set to a place that's generally readable, not just readable for the 'vagrant' user.