Debugging recently found issues

## Changes

- Added naming to collections to easliy identify which collection we
are in when debugging
- Realised that tags for tumblr items were not being created because
tumblr items had isDocument and isFile undefined as it is a virtual
document, which the collection isHTML required
- Updated isHTML to check for write:true instead of isDocument and
isFile
- Added isDocument and isFile defaults

## Choices
This leaves us with the following choices

### documents/files as types

- then partials,layouts would be inside the documents collection - very
bad
- can work around by having documents,files collections check for
write:true
- then we have write:false draft documents inside the documents
directory not inside the documents collection
- result is isDocument,isFile set appropriatly for types

### documents/files as directories

- then importers have problems
- can work around by having html,stylesheet collections check for
write:true
- result is isDocument,isFile undefined for imported documents