Yet more work for invasions, still not 100% yet.

* Invasions are now loaded from the API and inserted into the popup.
* Refactored a bit of code to resolve ambiguity in regards to what code does what.
* Removed extraneous `return`s and logging.
* Inserted some comments to help readability.
* Fixed up some formatting issues with the invasions HTML template.
* Fixed some incorrest styling in Popup.less
* Invasions are tracked seperately from alerts in the popup.
* Fixing the tab vs space situation.

Also note that because of some issues with firing events and manipulating dynamically/asynchronously added DOM elements that all "extra" information about alerts is permanently visible. Until I can hash out all the related problems, there will be no toggling like I intend.