Fix Implicitly Unwrapped nil value error in `XcodeSpec`
Revert "Fix Implicitly Unwrapped nil value error in `XcodeSpec`"

This reverts commit ee4717ddf291b54bdc87fca7174a9e3d63228445.
Test for `.Success` and `.Failure` of `otool` in `XcodeSpec`.
Extract `buildFolderURL.URLByAppendingPathComponent`… into func.
Increase type safety with nil matcher.
Revert "Extract `buildFolderURL.URLByAppendingPathComponent`… into func."

This reverts commit 5900120794b36c597efad2ccfa94730997e22095.
Revert "Test for `.Success` and `.Failure` of `otool` in `XcodeSpec`."

This reverts commit 366905e102d2a433a8a789754be3f1f313e3c089.
Split `output` into `otoolResult` and `output`.
This allows us to test `otoolResult.error()`.
Map `Result` of `otool`.
Move architecture expectations out of `otoolResult`'s map.
Merge pull request #211 from jdhealy/fix-implicitly-unwrapped-error-in-XcodeSpec-3

Fix Implicitly Unwrapped nil value error in `XcodeSpec` using Optional NSString