[x] update current signWithXXX and loginWithXXX to call new server api
[x] return User record in signup, login and whoami response
[x] remove APIs that are calling server user:xxx
[x] remove saveUser
[x] remove getUserByXXX
[x] remove User object (the original user object returned in signup/login api), the followings are needed to replace the api provided by the original User object
[x] add add/get/deleteRoles api to skygear.auth, work with user id and role object
[x] make ACL and Relation object consumes User record instead of User object
feature: https://github.com/SkygearIO/features/issues/48 server issue: https://github.com/SkygearIO/skygear-server/issues/393
signup(authData, password, [profile])login(authData, password)signWithXXXandloginWithXXXto call new server apiUserrecord in signup, login and whoami responseuser:xxxsaveUsergetUserByXXXUserobject (the original user object returned in signup/login api), the followings are needed to replace the api provided by the originalUserobjectadd/get/deleteRolesapi toskygear.auth, work with user id and role objectACLandRelationobject consumesUserrecord instead ofUserobject