DOC: link to travis setup instructions in CONTRIBUTING.md
DOC: link to travis setup instructions in CONTRIBUTING.md

cython-testbed/pandas,MJuddBooth/pandas,rs2/pandas,jorisvandenbossche/pandas,nmartensen/pandas,Winand/pandas,amolkahat/pandas,GuessWhoSamFoo/pandas,jreback/pandas,toobaz/pandas,dsm054/pandas,pandas-dev/pandas,linebp/pandas,jreback/pandas,datapythonista/pandas,harisbal/pandas,winklerand/pandas,nmartensen/pandas,gfyoung/pandas,louispotok/pandas,kdebrab/pandas,MJuddBooth/pandas,nmartensen/pandas,louispotok/pandas,DGrady/pandas,jorisvandenbossche/pandas,cbertinato/pandas,winklerand/pandas,louispotok/pandas,winklerand/pandas,louispotok/pandas,jmmease/pandas,harisbal/pandas,jmmease/pandas,linebp/pandas,Winand/pandas,jorisvandenbossche/pandas,MJuddBooth/pandas,GuessWhoSamFoo/pandas,amolkahat/pandas,zfrenchee/pandas,rs2/pandas,linebp/pandas,cbertinato/pandas,louispotok/pandas,toobaz/pandas,nmartensen/pandas,gfyoung/pandas,zfrenchee/pandas,pandas-dev/pandas,winklerand/pandas,kdebrab/pandas,toobaz/pandas,pratapvardhan/pandas,TomAugspurger/pandas,dsm054/pandas,cbertinato/pandas,DGrady/pandas,dsm054/pandas,gfyoung/pandas,datapythonista/pandas,cython-testbed/pandas,cython-testbed/pandas,kdebrab/pandas,pratapvardhan/pandas,Winand/pandas,zfrenchee/pandas,zfrenchee/pandas,Winand/pandas,gfyoung/pandas,DGrady/pandas,GuessWhoSamFoo/pandas,toobaz/pandas,winklerand/pandas,GuessWhoSamFoo/pandas,TomAugspurger/pandas,cython-testbed/pandas,jmmease/pandas,TomAugspurger/pandas,pandas-dev/pandas,amolkahat/pandas,nmartensen/pandas,cython-testbed/pandas,datapythonista/pandas,cbertinato/pandas,rs2/pandas,cbertinato/pandas,jreback/pandas,linebp/pandas,datapythonista/pandas,harisbal/pandas,jmmease/pandas,jreback/pandas,MJuddBooth/pandas,amolkahat/pandas,amolkahat/pandas,kdebrab/pandas,linebp/pandas,TomAugspurger/pandas,jreback/pandas,gfyoung/pandas,winklerand/pandas,jorisvandenbossche/pandas,zfrenchee/pandas,DGrady/pandas,dsm054/pandas,Winand/pandas,linebp/pandas,rs2/pandas,pratapvardhan/pandas,jmmease/pandas,kdebrab/pandas,Winand/pandas,DGrady/pandas,pandas-dev/pandas,jmmease/pandas,DGrady/pandas,pratapvardhan/pandas,harisbal/pandas,pratapvardhan/pandas,nmartensen/pandas,toobaz/pandas,dsm054/pandas,harisbal/pandas,GuessWhoSamFoo/pandas,MJuddBooth/pandas