auto merge of #251 : alexcrichton/cargo/print-the-failure, r=wycats

This previously relied on the test itself printing failure, but this is not
always the case for test which, for example, segfault. Instead this ensures that
*something* is always printed when a test fails, normally a short blurb about
what executable failed to run.

diff --cc tests/test_cargo_test.rs
Simple merge