add support for comma-delimited list of configuration directories
Specs no longer use "echo -n" as a test shell command

The -n option to echo is only supported by certain shells (e.g. bash) and as a result the tests can fail on certain platforms - OSX being one example. This removes the use of the -n option and adjusts expected output values accordingly.
Merge pull request #572 from tleach/mac-specs

Specs no longer use "echo -n" as a test shell command
Merge pull request #568 from grepory/multiconfigs

add support for comma-delimited list of configuration directories
[config_dirs] :config_dir -> :config_dirs, as it's now an array
Merge pull request #573 from portertech/config_dirs

:config_dir -> :config_dirs, as it's now an array