Replace with `concat:[RACSignal return:]]`

Update the docs and clarify the request provided and response expectations

Re-add that Squirrel adds `Accept: application/json` to the request.

Also log errors that occur removing owned bundle locations.

Log when we can’t get the running application code signature

Don’t crash.

Prune temporary directories before performing first update check

Not just before beginning automatic updates.

Conflicts:
SquirrelTests/SQRLInstallerSpec.m

Conflicts:
Squirrel.xcodeproj/project.pbxproj

Add steps to Readme

This avoids the state parameters being passed to the root installer, and forces the root install...

Store the installation attempts in the preferences, needs to be cleared

This is the client sent structure and has no ShipIt internals included, all ShipIt state will be...

Ensures we have mutual exclusion when reading the state, because other processes may be writing ...

ShipIt state is now in the prefs too.

Previously it read from disk, modifications to the state aren’t stored there anymore.

It knows nothing of the directory manager.

Don’t `__bridge` cast the `AuthorizationRef`

Conflicts:
External/ReactiveCocoa

Protect against symlink attacks

Conflicts:
Squirrel/SQRLShipItLauncher.m

Update URLs to Mantle repository

This change isn’t strictly necessary due to automatic redirection, but
let’s keep our links fresh.

Note that we're dependent on ReactiveCocoa and Mantle