Fixed links in Software Defined radio post
removed random junk from index,md
Removed join us button, as requested by committee
Revert "Removed join us button, as requested by committee"

I had the wrong idea, whoos >.<

This reverts commit 7052bcb1b1253bbc534e81dab211c59024ce5755.
Removed the "Sign Up" button from the carousel, as it's already in the site nav bar
Removed two &nbsp;s which had no place
Removed target="_blank" from links on SDR blog post
Removed another target=blank. It was hiding, I swear.
Merge pull request #68 from graymalkin/master

Fixes links in SDR post and removes a double of the joinus buttons.