cargo-run: support target and release the same as cargo-build
Merge remote-tracking branch 'cmr/master'

Conflicts:
	src/cargo/ops/cargo_run.rs
	tests/test_cargo_run.rs
Fix cargo-run rebasings and tests

Closes #443
auto merge of #455 : alexcrichton/cargo/cargo-run, r=alexcrichton

Just some minor test fixes.