Any IOErrors are now captured in ResultT's liftIO using try and converted into
'Bad'. This prevents IO exceptions from leaking into ResultT code and allows
them to be handled in a pure way inside ResultT's sum type.

It is still possible to avoid 'try' by using 'lift' or 'ResultT' directly,
therefore it's recommended to use 'liftIO' only.

Note that other, non-IO exceptions, such as PatternMatchFail, aren't handled.
This might be revised in future, if desired.

Signed-off-by: Petr Pudlak <pudlak@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>