Remove resource value APIs until they can be redesigned
Do our own URL reading
Rename and document "contents missing" exception
Merge branch 'refs/heads/v0-develop' into feature/direct-url

Conflicts:
	GBSFileWrapper/GBSFileWrapper-Info.plist
	GBSFileWrapperTests/GBSFileWrapperTests-Info.plist
Implement our own -writeToURL:options:error:
Implement atomic writes
Use file reference URLs to increase robustness against stuff changing on disk
Correctly get names for directory children
Add a small utility category
Add some minor docs for the GBSFileWrapperDataSource
Add (currently half-implemented) resource value calls
Translate file ref URLs back to path URLs
Support for resource values from -initWithURL:…
Support for mutating resource values
Support for resource values from NSFileWrappers
Remove resourceValue-less initWithDataSource:
Exclude weird xccheckout file
Add lists of resource value keys
Fix failure to return newly-fetched resource values
Set resource values on -writeToURL:…