Add missing Carthage support

[DmitryPR]

For some reason the Cartfile was missing so when adding this library using Carthage the SWXMLhash dependency did not get downloaded

[DmitryPR]

Hi, can this get merged?

[ystrot]

Hi Dmitry,

Sorry for delay. Macaw team are not using Carthage, so it needs a bit more time to check this. We'll try to merge it on the next week.

[amarunko]

Hi, @DmitryPR, can you explain in little details, what wrong with automatical fetching by Carthage? For me everyting work as expected in current setup.

[DmitryPR]

Hello, the integrators who are using Macaw with Carthage need to supply

github "Exyte/Macaw" ~> 0.9.3

and

github "drmohundro/SWXMLHash" == 4.7.5

Because Macaw uses this dependency

This is incorrect behaviour as all the dependencies that Macaw rely on should be listed in the Cartfile so that when the integrators specify github "Exyte/Macaw" ~> 0.9.3 the SWXMLHash would be downloaded along with Macaw

[amarunko]

@DmitryPR, so, I added in cartfile only Macaw dependency, follow Carthage instructions in readme, project successfully run on OS X and iOS. Found in dependencies folder SWXMLHash, sorry I'm not an expert in Carthage, maybe I missed something, can you explain, please.

[DmitryPR]

So here is the setup:

We have an iOS library which has Macaw as a dependency using Cocoapods where the SWXMLHash is specified as dynamic dependency
https://github.com/exyte/Macaw/blob/master/Macaw.podspec#L43

After our library is integrated into another project it requires dynamic libraries to be loaded along side with our iOS library:
https://github.com/salemove/ios-carthage-integration/blob/master/Cartfile

Here we have to define SWXMLHash as a Carthage dependency because Macaw brings this dependency in
https://github.com/salemove/ios-bundle/blob/master/Cartfile

This PR makes sure that when there is no need to manually add
github "drmohundro/SWXMLHash" == 4.7.5

as it should be listed in your repository in Carthage file

[amarunko]

@DmitryPR, I checked, you are right, thank you for your work! One more moment, can you change equality in dependency == to ~>, please. As soon you change this, PR will be merged.