replace error_check with assert_zeromq
replace error_check with assert_zeromq

Here we rewrite the error_check method to be a lot simpler 'return if no error,
raise if there is'.

Due to the way MCollective already catches and displays exceptions, there's no
real need to unpack the callers stacktrace (well apart from we always start the
stacktrace one frame lower than would be ideal, but that's cosmetic vs writing
less code)

puppetlabs/mcollective-zeromq-connector