added docs for activating a version
Fixing another obsolete default_version_id reference
exclude _assets from validation
fix invalid responses
affixed reccomendation to download library
Add attachment-info to webhooks/parse

Closes #450
Merge pull request #440 from jdzimmerman/MEME-2032-b

Fixing another obsolete default_version_id reference
Merge pull request #431 from bsorin/meme-2030

Teslago: Add endpoint to activate a version
Update spam_checker.html

Adding clarification of numeric settings.
Merge pull request #454 from sendgrid/develop

deploy!