Only build carthage scheme for CI by default
Only build carthage scheme for CI by default

It encompasses CarthageKit and its tests already, so no need to build
everything.

erichoracek/Carthage,erichoracek/Carthage,NachoSoto/Carthage,flovilmart/Carthage,flovilmart/Carthage,0xced/Carthage,abbeycode/Carthage,abbeycode/Carthage,NachoSoto/Carthage,0xced/Carthage,abbeycode/Carthage,0xced/Carthage,flovilmart/Carthage,erichoracek/Carthage,erichoracek/Carthage,NachoSoto/Carthage,abbeycode/Carthage