Change aggregator dropdown in the options to be dynamic based on localStorage

[machawk1]

When the fallthrough logic is invoked in #369 (via #316, issue-316), this hard-coded HTML does not reflect the localStorage value.

[machawk1]

0d5237c partially solves this but when the aggregator is set per #369, the localStorage value reads as null and is reset to the default.

To replicate, while the ODUCS MemGators instance is down.

1. Open the Mink options page in Chrome
2. Verify that the default aggregators populate the dropdown
3. Visit a page that causes the fallthrough logic to be invoked, which should set the aggregator value to aggregator.matkelly.com
4. Open the console on the options page in Chrome
5. Reload the options page, note that the dropdown is now blank (it should have reordered the items in the dropdown to reflect the new precedence
6. Reload the options page, note that the default has been restored