Major Update

Issues fixed:

• #19
• #20
• #21
• #22 - Repository filtering has been implemented
• #24

Other Changes:

• Repository items are using CSS grid for layout
• Removed use of the avatar_url in a number of places within the "Activity" list where the avatar served no useful purpose.
• "To Top" handling is now internal to github-feeds.js
• Miscellaneous CSS adjustments
• Clean up