use https everywhere (#6574)

* use https everywhere

* use https links on the files that are left

Also, removed some broken links and updated redirections.

plugins/pow/pow.plugin.zsh

@@ -73,7 +73,7 @@ powed(){
 }
 
 # Restart pow process
-# taken from http://www.matthewratzloff.com/blog/2011/12/23/restarting-pow-when-dns-stops-responding
+# taken from https://www.matthewratzloff.com
 repow(){
   lsof | grep 20560 | awk '{print $2}' | xargs kill -9
   launchctl unload ~/Library/LaunchAgents/cx.pow.powd.plist