Memento Aggregators drop down is not initially populated

[machawk1]

In a clean install of Mink 3.0.1, pin the icon in the toolbar, visit a page, let it resolve, then right-click the icon to get to the options page. Note that the "Memento Aggregators" dropdown is not populated. Reload the options page and the options appear!

[machawk1]

This might be a race condition wherein the aggregators are loaded into localstorage at the same time the initial page is loaded. Once the aggregators are in LS and the page is reloaded, the LS is then populated and thus the dropdown can be populated.

[machawk1]

Related to #390