Fixes for SitestreamController

This patch includes a number of fixes for SitestreamController

SitestreamController
- Fixed getInfo(streamId,userId):
    * BUG: This method's request was not signed and always failed authorization.
        * FIX:Modified constructRequest to sign all requests, not just POSTs.
    * ISSUE: This method should not take a userId
        * FIX: added the correct method 'getInfo(streamId)', existing method is now deprecated
- Added addUsers(streamId,userIds): NEW FEATURE
    * Support for adding up to 100 userIds per request as per docs
    * addUser(streamId, userId) was not modified
- Added removeUsers(streamId, userIds): NEW FEATURE
    * Support for removing up to 100 userIds per request as per docs
    * removeUser(streamId, userId) was not modified

SitestreamControllerTest
- added tests for existing methods: getInfo, addUser, removeUser
- added tests for new methods: addUsers, removeUsers

HttpConstants
- constructRequest(host,endpoint,auth): BUG FIX
    * BUG: GET endpoints are not signed in constructRequest(host,endpoint,auth)
        * FIX: All requests are now signed if an auth is supplied