Remove VALID_DATETIME regex
Remove timestamp and linkmap utilities from APIResource

Each class will handle timestamp and linkmaps for greater transparency
Remove input validation from APIResource methods

This class should do one thing: call the API and respond with the output

Input validation will be moved to callers of these methods
Implement constructors for Microcosms, Items, and meta types
Formatting
Add optional site attributes
Add remaining attributes for existing API resource classes
Remove generic pagination code
Use MicrocosmList resource for listing microcosms
Rearrange constructors and classmethods
Define constructors for Comment, Conversation, Event resources
Consistent comment style
Return Event instance when retrieving an event
Avoid Python keyword clash
Remove unused 'header.html' template
Fix failing BuildURL tests
Remove hardcoded subdomain in tests
Merge branch 'consolidate-api-types' of github.com:mattcottingham/microweb into consolidate-api-types
Update profile attributes in base.html
Style