fix(import): save model after assigning deck

[ryenbeatty]

Fixes #17

This fixes an issue where all imported cards are added to the 'Default' deck, instead of the deck specified in the plugin config.

Resources: https://forums.ankiweb.net/t/importnotes-always-adds-cards-to-default-deck/1690/3 https://addon-docs.ankiweb.net/#/getting-started?id=the-collection