Check for existence of automake, autoconf in bootstrap.sh

[ayleph]

If someone executes ./bootstrap.sh without automake and autoconf installed, the system will print warnings about the files not being found then proceed to the git submodule commands whose output floods the terminal and may prevent the user from seeing the previous error output. Then the user is confused why there is no configure. I think we should update bootstrap.sh to check for the presence of automake and autoconf with which commands and terminate the script with an error message if one isn't found, rather than continuing wit git submodule actions.

[Christopher Allan Webber]

Good idea. I put "set -e" in the script. It should now fail if any of the commands in the script fail.