Splits out testflight and specs tasks

Updates thrust installer to conditionally check for Rakefile and include
separate rake tasks.
Changes config load dir to be cwd

rather than relative to the .rake files
Refactors XcodeConfig to ThrustConfig

Also makes it a class with instance variables instead of a Module that gets included

Updated both rake files to use the instance.
Fixes missing reference to thrust instance

during testflight deploys
Fixes thrust installer to correctly install rake tasks

Installed in a folder off the project root called 'thrust'

It will now not modify the Rakefile if it exists and instead will instruct the user about how to import the new tasks into their existing file.