Homepage UI improvements

[samuelsidler]

There's a few things on the homepage that need to get cleaned up:

• Padding between sections needs to match that of other pages (i.e. browse pages). Needs to be consistent both between the header and content and between each content block.
• On smaller-width devices (iPhone 5S), plugin icons do not appear in the cards. We should add them back and resize them to look good on those devices.