Install the latest bundler on Travis.
Install the latest bundler on Travis.

We're running into an issue with installing gems that _may_ be fixed by
a newer version of bundler. The error itself [1] may have been fixed by
Bundler#3559 [2].

1: "NoMethodError: undefined method `spec' for nil:NilClass"
2: https://github.com/bundler/bundler/pull/3559

deadmanssnitch/snitcher