I (unintentionally) uploaded a CL with a binary file, and Spacey tried to analyze it, resulting in a "token too long" error.

There are a couple issues with this:
 * Spacey shouldn't try to analyze binary files.
 * To process input with lines that are potentially long, bufio.Reader.ReadLine is preferred over bufio.Scanner.

Example task:
https://chromium-swarm.appspot.com/task?id=3c2628ef0575ef10&refresh=10&show_raw=1

Related discussion about bufio.Scanner:
https://stackoverflow.com/questions/21124327/how-to-read-a-text-file-line-by-line-in-go-when-some-lines-are-long-enough-to-ca