gitignore changes
Adds ModelsLibrary with utilities for working with sets of NetLogo models
Adds ModelLibraryCompiler and Messages
Adds Global to start model compilation at startup, along with StatusCacher
Adds "/model/statuses.json" route to get the compilation status of library models
Modify models.coffee to apply status styling to the list of models.
Big bunch of code cleanup
Merge pull request #157 from NetLogo/wip-model-status-api

Wip model status api
Create new http api for compiling

This includes:

- New compiler REST methods
- New widget serialization
- New widget view code
- New /tortoise page that has dynamic loading of non-standalone models