log SDK version and provide api for SDK version (#200)

* log SDK version and provide api for SDK version

* change SDK-version print to debugLevel

Author: jaeopt

OptimizelySDK/Optimizely/OptimizelyClient.swift

@@ -25,10 +25,13 @@ open class OptimizelyClient: NSObject {
 
     var sdkKey: String
     var config: ProjectConfig?
+
+    public var version: String {
+        return Utils.sdkVersion
+    }
 
     // MARK: - Customizable Services
 
-    // I only want to get this once from the handler service.
     lazy var logger = HandlerRegistryService.shared.injectLogger()!
 
     var eventDispatcher: OPTEventDispatcher {
@@ -37,8 +40,6 @@ open class OptimizelyClient: NSObject {
 
     // MARK: - Default Services
 
-    // TODO: [Tom] can we remove decisionService from RegsitryService?
-    
     var decisionService: OPTDecisionService {
         return HandlerRegistryService.shared.injectDecisionService(sdkKey: self.sdkKey)!
     }
@@ -85,6 +86,7 @@ open class OptimizelyClient: NSObject {
                               decisionService: DefaultDecisionService(userProfileService: userProfileService),
                               notificationCenter: DefaultNotificationCenter())
 
+        logger.d("SDK Version: \(version)")
     }
 
     /// Start Optimizely SDK (Asynchronous)