Include Swift-specific build settings on target creation

Only copy the required xcasset files into the user bundle

[Validator] Allows Swift pods to have a deployment target under iOS 8.0 ...

[XCConfigHelper] Adds $(inherited) to generated OTHER_SWIFT_FLAGS

Before all xcassets used in pod sources where unconditionally integrated into the bundle's car file, even if the xcasset file wasn't referenced by the podspec. Now only files, which are explicitly specified in the spec, will be integrated.

[Resolver] Shows an informative error message when there is no base specification found for a `:head` dependency.

Closes https://github.com/CocoaPods/CocoaPods/issues/3230.

[Validator] Lint dynamic libs for iOS > 7

Fix static binaries check

Allows the usage of `:head` dependencies even when the most recent published version was a pre-release.

Closes https://github.com/CocoaPods/CocoaPods/issues/3212.

Set FRAMEWORK_SEARCH_PATHS only when needed

We don't need to add $PODS_FRAMEWORK_BUILD_PATH, if there is no pod target, which should be build.
Fixes #3213.

Closes https://github.com/CocoaPods/CocoaPods/issues/2990.

See 122c8d98

Logical expressions are hard.