Add option to download file using pure bash (install_bigfix.sh)

[jgstew]

https://www.shell-tips.com/2011/07/09/download-files-from-a-bash-shell/

Apparently there is a way to download files using pure bash on some systems.

not sure how to detect if /dev/tcp is enabled for the version of bash on the system.

Related:

• http://unix.stackexchange.com/questions/241174/dev-tcp-not-found
• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=146464