Makes installer respect INSTALLER_BRANCH environment
Makes installer respect INSTALLER_BRANCH environment

So we can test them with a command like:

    b=netj-installers
    INSTALLER_BRANCH=$b \
    bash <(curl -fsSL https://raw.github.com/HazyResearch/deepdive/$b/util/install.sh)

Atlas7/deepdive,sky-xu/deepdive,topojoy/deepdive,closedLoop/deepdive,zifeishan/deepdive,vsoch/deepdive,topojoy/deepdive,HazyResearch/deepdive,RTsWorld/deepdive,vasyvas/deepdive,nvoron23/deepdive,infinitespace/deepdive,infinitespace/deepdive,Atlas7/deepdive,Gela/deepdive,kod3r/deepdive,maalmeida1837/deepdive,nvoron23/deepdive,vsoch/deepdive,sky-xu/deepdive,topojoy/deepdive,maalmeida1837/deepdive,wgapl/deepdive,kod3r/deepdive,nvoron23/deepdive,zifeishan/deepdive,Atlas7/deepdive,Atlas7/deepdive,vasyvas/deepdive,HazyResearch/deepdive,wgapl/deepdive,Gela/deepdive,shahin/deepdive,nvoron23/deepdive,shahin/deepdive,kod3r/deepdive,sai16vicky/deepdive,infinitespace/deepdive,RTsWorld/deepdive,maalmeida1837/deepdive,Atlas7/deepdive,topojoy/deepdive,Gela/deepdive,RTsWorld/deepdive,sai16vicky/deepdive,maalmeida1837/deepdive,Gela/deepdive,sai16vicky/deepdive,wgapl/deepdive,HazyResearch/deepdive,maalmeida1837/deepdive,HazyResearch/deepdive,wgapl/deepdive,closedLoop/deepdive,zifeishan/deepdive,vsoch/deepdive,vasyvas/deepdive,AlexisBRENON/deepdive,zifeishan/deepdive,wgapl/deepdive,topojoy/deepdive,closedLoop/deepdive,kod3r/deepdive,infinitespace/deepdive,zifeishan/deepdive,kod3r/deepdive,vsoch/deepdive,infinitespace/deepdive,vsoch/deepdive,vasyvas/deepdive,closedLoop/deepdive,Gela/deepdive,nvoron23/deepdive,infinitespace/deepdive,AlexisBRENON/deepdive,AlexisBRENON/deepdive,AlexisBRENON/deepdive,RTsWorld/deepdive,RTsWorld/deepdive,sai16vicky/deepdive,closedLoop/deepdive,sai16vicky/deepdive,vasyvas/deepdive,AlexisBRENON/deepdive