Catch and silence errors in installing IPython completers.
Catch and silence errors in installing IPython completers.

Avoid problems with older versions of IPython (pre 0.11)

Closes gh-230

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