v0.4.0

• New: Check if domain is proxied before raising CNAME/A record expectation errors (#21)
• Improved: served_by_pages? check is now a HEAD request, accepts gzip encoding, has a 10 second time out, and sends a descriptive user agent (#23)
• Fixed: Use Addressable::URI rather than Ruby's native URI class which better conforms to the RFC when testing domains with underscores (#25)
• Development: Stub all net requests when testing (#24)