#48 create 'app_name' variable for template use

[Nick Silkey]

Much like how org_name exists, it would be great if there were an app_name variable. Use case being Foobar University using Filelocker and branding the service 'Foobar Secure File Transfer'. Given the context in the templates, org_name should certainly be set to Foobar University. Existing templates hardcode the term 'Filelocker' throughout. To keep Foobar University from hacking on the templates to support 'Foobar Secure File Transfer' throughout the verbiage, a variable like app_name would suit nicely.

Footers defaulting to keeping attribution to the Filelocker project is tenable.

-nick