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?
Without it I get:
```
src/drivers/lcd/mod.rs:192:3: 204:4 error: failed to find an implementation of trait drivers::chario::CharIO for drivers::lcd::test::TestLCD
```