Resolve https://github.com/groupon/DotCi/issues/34
by providing development better info when merge conflicts are detected

    * https://developer.github.com/v3/repos/merging
    * https://github.com/blog/843-the-merge-button

using bash { } per http://mywiki.wooledge.org/BashPitfalls#cmd1_.26.26_cmd2_.7C.7C_cmd3
instead of bash trap per http://linux.die.net/Bash-Beginners-Guide/sect_12_02.html