Easy Digital Downloads - AWeber 2.0.9

Improvement: Add an empty "Select a List" dropdown option to help better convey when no list is selected.
Dev: Compatibility with EDD 3.0.
Dev: Check minimum requirements before booting plugin. (Actual requirements have not changed.)
Dev: Update API library.
Dev: Refactor how the licensing is instantiated.
Dev: Allow the EDD_Aweber hooks to be unhooked.

Fix: It was impossible to fully disconnect an account and reconnect another.
Fix: Lists were not able to be refreshed manually.
New: Moved settings to Subsection under the Extensions tab.

-Tweak: Added an option to define if checkbox is checked or not by default on checkout.