STORE-387 and STORE-386 Fixes

This pull request contains the fixes for ;
 STORE-387 URL: https://wso2.org/jira/browse/STORE-387
 STORE-386 URL: https://wso2.org/jira/browse/STORE-386

The fixes for both these issues involved obtaining the Identity Provider URL from the appropriate config file (store and social). The user can specify the IDP url by using the identityProviderURL in the configuration files.

In addition, the following syntax allows the local ip to be picked up.

 "identityProviderURL": "%https.carbon.local.ip%/admin/samlsso",

If the user specifies "%http.carbon.local.ip%/admin/samlsso" then http port is picked up.