implements atomic vertex Read-Modify-Write

### Expected behavior 期望表现
implements a mechanism that can read-modify-write one vertex atomically.

#### Example:

##### before

`savings(property) of account(Vertex) is 100;`

##### operation

`increase savings of account 100 in different threads simultaneously.`

##### after

`two thread completed. And savings(property) of account(Vertex) must be 300`

### Specifications of environment 环境信息
- hugegraph version: v0.8