Nighthawk Wallet Design & Development Grant

[aiyadt]

UPDATE: The problem pdf lib was replaced with an Apache License 2.0 one.
Thanks to @kayabaNerve & @GGuy for the inputs.

@NighthawkApps

Switch to PdfBox with Apache License 2.0 for exporting PDFs following community recommendation towards resolving issues around licensing and making the Android codebase compilable by end-users.