Fixes #129
Should only add a path to $binaries if there is a value assigned to the key in config.txt.
searches $PATH for just the basename, not a full path, if that's what was passed in.
get_bin just gets any value already in $binaries.
incorrectly catching diff errors in test_all.pl
Merge branch 'master' into issue-127

This reverts commit bf62e39245fcd5ca564f8f6136be05389b02b581.