ARROW-1498: Add CONTRIBUTING.md to .github special directory
ARROW-1498: Add CONTRIBUTING.md to .github special directory

I don't think it's necessary to have an ISSUE_TEMPLATE.md right now, but we can add one in the future if it is deemed useful

Author: Wes McKinney <wes.mckinney@twosigma.com>

Closes #1176 from wesm/ARROW-1498 and squashes the following commits:

462e766e [Wes McKinney] Add CONTRIBUTING.md to .github special directory

cpcloud/arrow,dremio/arrow,pcmoritz/arrow,dremio/arrow,itaiin/arrow,yufeldman/arrow,cpcloud/arrow,pcmoritz/arrow,kou/arrow,tebeka/arrow,NonVolatileComputing/arrow,kou/arrow,dremio/arrow,yufeldman/arrow,icexelloss/arrow,siddharthteotia/arrow,dremio/arrow,wesm/arrow,kou/arrow,renesugar/arrow,apache/arrow,pcmoritz/arrow,siddharthteotia/arrow,siddharthteotia/arrow,xhochy/arrow,itaiin/arrow,pcmoritz/arrow,icexelloss/arrow,xhochy/arrow,siddharthteotia/arrow,yufeldman/arrow,xhochy/arrow,yufeldman/arrow,icexelloss/arrow,pcmoritz/arrow,dremio/arrow,xhochy/arrow,majetideepak/arrow,cpcloud/arrow,apache/arrow,xhochy/arrow,itaiin/arrow,xhochy/arrow,majetideepak/arrow,laurentgo/arrow,apache/arrow,yufeldman/arrow,pcmoritz/arrow,wesm/arrow,wagavulin/arrow,wesm/arrow,NonVolatileComputing/arrow,cpcloud/arrow,wesm/arrow,majetideepak/arrow,xhochy/arrow,laurentgo/arrow,wesm/arrow,wagavulin/arrow,majetideepak/arrow,yufeldman/arrow,siddharthteotia/arrow,icexelloss/arrow,siddharthteotia/arrow,icexelloss/arrow,renesugar/arrow,itaiin/arrow,laurentgo/arrow,kou/arrow,dremio/arrow,kou/arrow,NonVolatileComputing/arrow,majetideepak/arrow,wesm/arrow,siddharthteotia/arrow,xhochy/arrow,kou/arrow,laurentgo/arrow,laurentgo/arrow,apache/arrow,pcmoritz/arrow,majetideepak/arrow,itaiin/arrow,NonVolatileComputing/arrow,xhochy/arrow,wesm/arrow,icexelloss/arrow,icexelloss/arrow,yufeldman/arrow,laurentgo/arrow,renesugar/arrow,laurentgo/arrow,laurentgo/arrow,wagavulin/arrow,kou/arrow,apache/arrow,yufeldman/arrow,dremio/arrow,xhochy/arrow,laurentgo/arrow,laurentgo/arrow,pcmoritz/arrow,apache/arrow,xhochy/arrow,renesugar/arrow,renesugar/arrow,wagavulin/arrow,pcmoritz/arrow,apache/arrow,siddharthteotia/arrow,kou/arrow,itaiin/arrow,majetideepak/arrow,renesugar/arrow,renesugar/arrow,majetideepak/arrow,cpcloud/arrow,renesugar/arrow,wagavulin/arrow,tebeka/arrow,pcmoritz/arrow,renesugar/arrow,NonVolatileComputing/arrow,dremio/arrow,itaiin/arrow,icexelloss/arrow,NonVolatileComputing/arrow,apache/arrow,yufeldman/arrow,NonVolatileComputing/arrow,tebeka/arrow,majetideepak/arrow,apache/arrow,itaiin/arrow,tebeka/arrow,dremio/arrow,renesugar/arrow,dremio/arrow,majetideepak/arrow,itaiin/arrow,majetideepak/arrow,kou/arrow,itaiin/arrow,renesugar/arrow,siddharthteotia/arrow,NonVolatileComputing/arrow,apache/arrow,cpcloud/arrow,NonVolatileComputing/arrow,wagavulin/arrow,apache/arrow,itaiin/arrow,tebeka/arrow,wagavulin/arrow,renesugar/arrow,cpcloud/arrow,siddharthteotia/arrow,xhochy/arrow,pcmoritz/arrow,icexelloss/arrow,renesugar/arrow,icexelloss/arrow,cpcloud/arrow,laurentgo/arrow,itaiin/arrow,cpcloud/arrow,yufeldman/arrow,wagavulin/arrow,apache/arrow,wesm/arrow,icexelloss/arrow,kou/arrow,xhochy/arrow,apache/arrow,wesm/arrow,itaiin/arrow,cpcloud/arrow,renesugar/arrow,cpcloud/arrow,majetideepak/arrow,majetideepak/arrow,majetideepak/arrow,laurentgo/arrow,wagavulin/arrow,kou/arrow,tebeka/arrow,wesm/arrow,tebeka/arrow,cpcloud/arrow,pcmoritz/arrow,icexelloss/arrow,majetideepak/arrow,cpcloud/arrow,pcmoritz/arrow,wesm/arrow,itaiin/arrow,cpcloud/arrow,dremio/arrow,icexelloss/arrow,NonVolatileComputing/arrow,yufeldman/arrow,wesm/arrow,kou/arrow,kou/arrow,NonVolatileComputing/arrow,itaiin/arrow,tebeka/arrow,wesm/arrow,wagavulin/arrow,pcmoritz/arrow,apache/arrow,wagavulin/arrow,kou/arrow,tebeka/arrow,tebeka/arrow,wesm/arrow,laurentgo/arrow,xhochy/arrow,icexelloss/arrow,laurentgo/arrow,pcmoritz/arrow,wagavulin/arrow,renesugar/arrow,laurentgo/arrow,siddharthteotia/arrow,xhochy/arrow