Final polishes for 2.1 release

[bquinn]

• Update documentation - look for TODO in the doc file
• Update protobufs to 2.1
• Add mention of the TypeScript type to guidelines
• Finish adding unit tests for 1.4 and 2.1 for new additions and changes
• Convert "validating" section to "tools" and mention the typescript type, ninjs generator, remove reference to heroku validator that doesn't exist any more