subscription page code refactoring as per peer reviews

Conflicts:
	components/andes/org.wso2.carbon.andes.core/src/main/java/org/wso2/carbon/andes/core/internal/registry/SubscriptionManagementBeans.java
	components/andes/org.wso2.carbon.andes.core/src/main/java/org/wso2/carbon/andes/core/internal/util/SubscriptionManagementConstants.java
resolved issues caused during conflict resolution
Merge pull request #43 from hastef88/subscription_ui_refactor_rebased

Subscription ui refactor rebased