Remove check for bash usage

Remove check for bash usage

Arbitrarily restricting ourselves from using bash because developers on
platforms like netbsd don't want to install bash from ports doesn't
make sense.  Any non-trivial shell script is likely to use features
like arrays or string manipulation that are poorly supported (if at
all) by sh, and the continued bumping of the number of expected bash
scripts is an indication that the check is not serving its purpose
anyway.

Along with removing the check, all shebang references to /bin/bash
have been replaced with /usr/bin/env bash in an attempt to be more
compatible across different hosts.

Change-Id: Ief72dc380cc88af38959c330897e2c127e33c332
Closes-Bug: #1440824