v0.2.0

• Breaking change! Removed UserQuery, use the unified Query instead.
• Breaking change! Add new Type CloudError replaced Error and ErrorWithCode.
• Breaking change! Add Files.UploadFromLocalFile replaced Files.UploadFromFile.
• Add built-in fields like SessionToken、Username on to User type.
• Add NewQuery on Users, Roles and Files.
• Add LogInByEmail and SignUpByEmail on Users.
• Auto recover from panic of cloud function handlers.
• Fix the validation of appKey and masterKey in LeanEngine server.
• Fix decode issues related to objectId and top-level arrays.