Added support for Carthage

[VincentSit]

What does this PR do?

Added support for Carthage.

Why are we doing this? Any context or related work?

Some people (such as me) need to use Carthage to avoid compiling third-party libraries over and over again. The existing project has no valid shared framework schemes. And the deployment version is iOS 10.0, which is different from the deployment version of iOS 9.0 for the library. The PR fixes these problems.

Major changes

• Updated README.md.
• Updated the Retry's version of example project to latest. (0.6.2)
• Downgraded the deployment target version of example project from iOS 10.0 to iOS 9.0.
• Share Retry scheme only, cancel share Retry-Example scheme.

Where should a reviewer start?

mkdir -p /tmp/RetryCarthage
cd /tmp/RetryCarthage
echo 'github "VincentSit/Retry" "master"' > Cartfile
carthage update

// Or combined.
mkdir -p /tmp/RetryCarthage && cd /tmp/RetryCarthage && echo 'github "VincentSit/Retry" "master"' > Cartfile && carthage update

Screenshots

➜  ~ mkdir -p /tmp/RetryCarthage && cd /tmp/RetryCarthage && echo 'github "VincentSit/Retry" "master"' > Cartfile && carthage update
*** Fetching Retry
*** Checking out Retry at "8d31ce7e7e114f668bde2492d1d06729ec7b92ca"
*** xcodebuild output can be found in /var/folders/k_/qmb6n50s0n70zgzj_008xwpc0000gn/T/carthage-xcodebuild.sZ6l0U.log
*** Building scheme "Retry" in Retry.xcworkspace
➜  RetryCarthage ls Carthage/Build/iOS/
503C3B60-B9A7-33E6-A9B3-389E9256F12F.bcsymbolmap Retry.framework
B42B0559-5F35-3B4C-ADB8-D389613399EA.bcsymbolmap Retry.framework.dSYM

Others

If you decide to accept and merge this PR, to make Carthage work, you may need to release a new version, since the current version does not include these changes. Otherwise the user needs to specify the branch in Cartfile to work, like github "icanzilb/Retry" "master".

[lcd1232]

@icanzilb could you merge it?

[icanzilb]

@lcd1232 unfortunately, supporting Carthage isn't a goal for this package. You can make your own fork for your project of course