Use activeTab permission

[justincy]

Whenever a new widget/scraper is added we have to update the extension's permissions. When an existing user downloads the update with the permission change it will disable the extension and show a warning in the settings window (which is hard to find unless you notice the button turned orange are curious enough to figure out why).

This is one of two big reasons why I haven't added support for more sites (the other is testing; hard to keep up with changes to websites).

We can probably avoid this issue by using the activeTab permission. It will require a small refactor:

• Be a browserAction instead of a pageAction (show the button at all times in the toolbar; handle case where the icon is clicked on a page with no recognizable data; probably just show the blank fields).
• Instead of the person data being loaded by default when the user navigates to a page, we will have to wait to process the data when the user clicks on the icon. This will require us to show a loading icon in the popup until the data is loaded.

[justincy]

I was wrong about being required to turn it into a browserAction but I might do that anyways. Having the button in the toolbar is less confusing to users (where'd the button go!?!?!) and fits better with my long term vision.

[justincy]

In the background script we will have code that listens for a click on the toolbar icon and then injects code into the current page:

chrome.browserAction.onClicked.addListener(function(tab) {
  chrome.tabs.executeScript(null, {
    file: 'content-script.js'
  });
});

content-script.js would be a thin wrapper around genscrape to gather the data (if it exists) and send it to the background page.

genscrape().on('data', function(data){
  chrome.extension.sendRequest({
    type: 'person_info',
    data: data
  });
});

This would significantly simplify manifest.json too by getting rid of the entire content_scripts section (the logic for that would be moved into genscrape).