Add a travis.yml

[orta]

Adds support for running the whole thing via CI. Here's the Dangerfile.swift

import Danger

print("Evaluating Dangerfile")

let danger = Danger()

print("Modified:")
for file in danger.git.modifiedFiles {
    print(" - " + file)
}

warn("Warning: bad stuff")
fail("Failure: bad stuff happened")
markdown("## Markdown for GitHub")

[DangerCI]

	Messages
📖	Just verifying this continues to work.

Generated by 🚫 dangerJS