Correctly handles wrongly named issues — closes #18

That CPU issue was caused by forever-lasting while loop on https://github.com/jschmid1/reviewlette/blob/80278ca6aead2136ab5723fa126260a11e0f1df6/lib/reviewlette.rb#L152-L154
By this commit we're taking into the account the case when the card cannot be found by the issue title — we're logging the error and just skipping the issue.