ARROW-3350: [Website] Fix powered by links
ARROW-3350: [Website] Fix powered by links

Author: Amir Szekely <kichik@gmail.com>

Closes #2647 from kichik/patch-1 and squashes the following commits:

a122e5cf <Amir Szekely> Fix link & add PR link

icexelloss/arrow,laurentgo/arrow,laurentgo/arrow,apache/arrow,majetideepak/arrow,renesugar/arrow,xhochy/arrow,xhochy/arrow,laurentgo/arrow,wesm/arrow,tebeka/arrow,cpcloud/arrow,itaiin/arrow,kou/arrow,laurentgo/arrow,laurentgo/arrow,majetideepak/arrow,laurentgo/arrow,pcmoritz/arrow,apache/arrow,itaiin/arrow,icexelloss/arrow,laurentgo/arrow,renesugar/arrow,tebeka/arrow,majetideepak/arrow,pcmoritz/arrow,kou/arrow,renesugar/arrow,wesm/arrow,kou/arrow,itaiin/arrow,icexelloss/arrow,majetideepak/arrow,xhochy/arrow,xhochy/arrow,renesugar/arrow,kou/arrow,tebeka/arrow,renesugar/arrow,wesm/arrow,laurentgo/arrow,cpcloud/arrow,xhochy/arrow,renesugar/arrow,cpcloud/arrow,apache/arrow,pcmoritz/arrow,itaiin/arrow,xhochy/arrow,pcmoritz/arrow,majetideepak/arrow,xhochy/arrow,icexelloss/arrow,itaiin/arrow,cpcloud/arrow,majetideepak/arrow,kou/arrow,cpcloud/arrow,majetideepak/arrow,itaiin/arrow,itaiin/arrow,apache/arrow,wesm/arrow,kou/arrow,xhochy/arrow,pcmoritz/arrow,renesugar/arrow,tebeka/arrow,icexelloss/arrow,cpcloud/arrow,apache/arrow,renesugar/arrow,pcmoritz/arrow,majetideepak/arrow,wesm/arrow,xhochy/arrow,pcmoritz/arrow,tebeka/arrow,laurentgo/arrow,cpcloud/arrow,kou/arrow,icexelloss/arrow,wesm/arrow,cpcloud/arrow,pcmoritz/arrow,kou/arrow,renesugar/arrow,pcmoritz/arrow,cpcloud/arrow,wesm/arrow,laurentgo/arrow,apache/arrow,icexelloss/arrow,wesm/arrow,laurentgo/arrow,wesm/arrow,majetideepak/arrow,apache/arrow,renesugar/arrow,itaiin/arrow,xhochy/arrow,renesugar/arrow,itaiin/arrow,kou/arrow,cpcloud/arrow,icexelloss/arrow,icexelloss/arrow,laurentgo/arrow,kou/arrow,pcmoritz/arrow,tebeka/arrow,xhochy/arrow,pcmoritz/arrow,majetideepak/arrow,majetideepak/arrow,majetideepak/arrow,itaiin/arrow,itaiin/arrow,icexelloss/arrow,wesm/arrow,tebeka/arrow,apache/arrow,wesm/arrow,itaiin/arrow,wesm/arrow,xhochy/arrow,apache/arrow,kou/arrow,tebeka/arrow,icexelloss/arrow,itaiin/arrow,icexelloss/arrow,apache/arrow,pcmoritz/arrow,icexelloss/arrow,laurentgo/arrow,itaiin/arrow,renesugar/arrow,cpcloud/arrow,pcmoritz/arrow,kou/arrow,renesugar/arrow,xhochy/arrow,tebeka/arrow,apache/arrow,pcmoritz/arrow,wesm/arrow,cpcloud/arrow,apache/arrow,apache/arrow,wesm/arrow,majetideepak/arrow,laurentgo/arrow,cpcloud/arrow,pcmoritz/arrow,majetideepak/arrow,renesugar/arrow,cpcloud/arrow,xhochy/arrow,itaiin/arrow,apache/arrow,xhochy/arrow,renesugar/arrow,majetideepak/arrow,tebeka/arrow,kou/arrow,kou/arrow,icexelloss/arrow,laurentgo/arrow