Update for Xcode 7 Beta 5

[mrackwitz]

Seemingly there was undocumented semantic change to stdlib's Array.split, which caused the fail of one test. maxCount doesn't behave as documented. Passing 2 instead of 1 fixes the test.

Test Case '-[CommandantTests.OptionsTypeSpec CommandMode_Arguments__should_treat____as_the_end_of_valued_options_##_68]' started.
OptionSpec.swift:71: error: -[CommandantTests.OptionsTypeSpec CommandMode_Arguments__should_treat____as_the_end_of_valued_options_##_68] : failed - expected to equal <{ intValue: 42, stringValue: foobar, optionalFilename: filename, requiredName: --intValue }>, got <nil> (use beNil() to match nils)

[jpsim]

Changes look appropriate and confirmed as working, thanks!