Give more helpful error messages when deserializing elmi files

Provides an error message indicating incorrect compiler version or corrupt file.
Exit status will be 1 in either failure case and error message is printed to
stderr. Uses the same checks against interfaces.data as well as standard .elmi
files since both are susceptible to breaking in the same way.

The following will be displayed when an elmi file has a different compiler
version than the elm compiler that tries to load it:

    justin ~/Code/elm-lang.org/public/examples/Intermediate $ ~/Code/elm/dist/build/elm/elm Pong.elm
    Found build artifacts created by a different Elm compiler version. Please rebuilt cache/Pong.elmi and try again.

The following will be displayed when a file that cannot be deserialized is
encountered:

    justin ~/Code/elm-lang.org/public/examples/Intermediate $ ~/Code/elm/dist/build/elm/elm Pong.elm
    Got an error, 'demandInput: not enough bytes' at offset 10303 of cache/Pong.elmi.

    This error may be due to an outdated or corrupt artifact from a previous build. Please rebuild cache/Pong.elmi and try again.
Merge pull request #320 from jsl/313_verify_serialized_interfaces

Give more helpful error messages when deserializing elmi files