Add a project class prefix
Remove unused references to Specta from the Xcode project file
Silence Xcode version update recommendations
Add Apple's new CoreData.ConcurrencyDebug debugging launch argument to the project
For save blocks, change the BOOL "success" to "contextDidSave"

A state of NO passed to success was confusing to some users (rightfully so) — if a context has no changes and you call save on it, it will return NO via this parameter but nothing has actually gone wrong. Hopefully this is clearer.
It is the developer's responsibility to manage Core Data concurrency — don't handle workname changes via performBlock:
Rename rootContextChanged to rootContextDidSave, and return early if the context in the notification is not the default context
Remove unnecessary check for performBlockAndWait: method signature
Lots of concurrency fixes for the tests. Xcode 6 is required now, due to the use of XCTestExpectation.
I keep removing this, and missing that it's on the store coordinator, not the context… derp.
Move the logging statements into the block, so that they report the correct thread

Addresses #377
Modify the save options if necessary
Fix iOS sample project

Fixes #847
Update podspec to 2.3.0-beta.4