add thrift wrapper for meta and storage

[jievince]

Add some thrift wrapper about reading vertexes, edges and meta information.
test on a 3-node cluster:
192.168.8.16 is meta server ip, 45500 is meta listening port, nba is the space name to read.
run example python3 GetFullGraph.py 192.168.8.16 45500 nba
result:

scaning space nba
ok
tagName:  player
vid:  109
{'name': 'Tiago Splitter', 'age': 34}
vid:  119
{'name': 'Kevin Durant', 'age': 30}
vid:  129
{'name': 'Dwyane Wade', 'age': 37}
vid:  139
{'name': 'Marc Gasol', 'age': 34}
vid:  149
{'name': 'Ben Simmons', 'age': 22}
tagName:  team
vid:  209
{'name': 'Timberwolves'}
vid:  219
{'name': '76ers'}
vid:  229
{'name': 'Heat'}
tagName:  player
vid:  108
{'name': 'Boris Diaw', 'age': 36}
vid:  118
{'name': 'Russell Westbrook', 'age': 30}
vid:  128
...

[laura-ding]

Well done!

Could you add some tests in tests dir?

[jievince]

test_StorageClient.py failed.
docker-compose maps the metad listening port to a random port, but the test requires a fixed metad port to connect.

[jievince]

test still failed.
https://github.com/jievince/nebula-python/runs/975833289?check_suite_focus=true

[laura-ding]

Excellent!