Windows uses mix of CRLF and LF, so handle either when calling 'where'.
simplify; use the interfaces that are already there
add Cliver#dependency_unmet? interface
remove convenience method on Cliver::Assertion, since we already have one on Cliver
style fix: use single quotes where possible
now that we are using shellwords for escaping, we don't have to do so much work to sanitize.
document all of the things; clarify & unify command params