switched console.log for dust.log

in a production environment (client or server) it is not appropriate to
log errors to the console.
helpers now log errors via the dust.log method using the "INFO" key so
that it is possible to activate logging of error messages via the log
level that has been assigned to the dust core.
falling back to an noop function

if the built in log function of dust core is not accessible the logging
method is replaced by a noop to stay backwards compatible
Merge pull request #88 from zaphod1984/consoleLog

switched console.log for dust.log