update fileinput example to allow newer reflex

[gspia]

The fileinput example compiled with ghcjs but not with ghc nor ghcid. Thus, liftIO's were changed to liftJSM's (three changes).
It also seems that the return type getResult has changed causing a small modifications following line 53. The fromJSVal <=< toJSVal construction is something that bothers me a bit: can the compiler optimize that and is there a function that would do the transformation directly? (Or is this the way to do in this kind of situations?)
At the end the return can be simplified a bit as the transformation can give directly Text.

[ryantrinkle]

Thanks!