Switched main target build settings' "skip install" default settings to YES. (#391)

SnapKit.xcodeproj/project.pbxproj

@@ -506,6 +506,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "io.snapkit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_BUNDLE_PACKAGE_TYPE = FMWK;
 				PRODUCT_NAME = SnapKit;
+				SKIP_INSTALL = YES;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
 				VERSIONING_SYSTEM = "apple-generic";
@@ -525,6 +526,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "io.snapkit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_BUNDLE_PACKAGE_TYPE = FMWK;
 				PRODUCT_NAME = SnapKit;
+				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
 				VERSIONING_SYSTEM = "apple-generic";
 			};