More int type fixes and tests for drivers

Just pulled in nightly and got a whole bunch of errors like this:
```
error: cannot determine a type for this expression: cannot determine the type of this integer; add a suffix to specify the type explicitly
```

Not sure, may be this just a follow-up on rust-lang/rust#6023?
Right. you don't need curly braces if the statement is simple, if it spans a few lines you still add them for readability (although it's syntactically correct to drop them).