willingly ignore traceview missing libraries warning

Hi, we use oboe to send data to appneta, but in our infraestructure we have on demand scaled batch machines and systems that use the apps code that doesn't have traceview libraries and appneta stack installed. This is because we want to monitor app machines but no batchs, CI machines, development machines and the like.

This allows to skip traceview missing message in machines where stderr contents means that something is broken. by calling rake as

IGNORE_TRACEVIEW_WARNING=1 bundle exec rake -s task 

May be could be useful for other users.