v0.4.0

• 78a7685 Chore: Update release script to tweet out release info (@nzakas)
• ae84ae4 Upgrade: Bump acorn from 6.3.0 to 6.4.1 (#4) (@dependabot[bot])
• 1bab294 Chore: Add .gitattributes (@nzakas)
• 4b41385 Docs: Fix last example (closes #5) (@nzakas)
• 6b234be New: Add Env#first() method (@nzakas)
• 55b75bb Chore: Add funding link to package.json (@nzakas)
• 8d44670 Build: Update CI to include pull requests (@nzakas)