Report a detailed error when the snapshot image size doesn't match

[dblock]

In some cases you have a snapshot using a simulator of a different size. Instead of just reporting that the snapshot doesn't match, report that the sizes don't match (with the sizes included in the error).

It took me a while to figure out that the simulator running on Travis-CI was a 4'' one for example (no idea why that's the default, btw).

[x2on]

Could give me an example?
If the images doesn't have the same sizes the following error which both sizes appears :

FBSnapshotTestCaseDemoTests.m:32: error: -[FBSnapshotTestCaseDemoTests testExample] :
((comparisonSuccess__) is true) failed - Snapshot comparison failed: 
Error Domain=FBSnapshotTestControllerErrorDomain Code=3 "Images different sizes" 
UserInfo=0x8e27760 {
NSLocalizedFailureReason=referenceImage:{64, 64}, image:{34, 64}, 
NSLocalizedDescription=Images different sizes
}

[dblock]

Oh that's good. I think I am swallowing this error in https:/dblock/ios-snapshot-test-case-expecta.