based on graphviz

* fix the tooltip index error

* frontend add graph

* frontend add image for graph, images, histogram update

* add graph get url; fix scalar

* modify theme color

* modify right config theme color

* modify right config theme color

* delete the large graph.png

* delete console

* modified something in frontend directory

* modified gitignore

* remove node_modules

* modify the data format for graph

* add label for each edge in the graph data formate

* merge scalars and image

* update histogram layout and style

feature/glog to exception

auto graph placement

* change paths

* add setup

* add packages

* update

* install ready

* restore mock

* restore graph_test.sh

* move visualdl.py to visualdl as a script

* fix setup

* remove onnx_pb2.py

* fix server_test

* add package into tests.sh

* add protobuf-compiler for package

* recover .git

* change script bin visualdl_bin to visualDL

* add npm cache

* avoid build_frontend in travis-CI

* avoid frontend build in travis-CI

* add pips

* restore protobuf mannul installation

* install protobuf

* fix package

* fix tool

* add graph mock data

* rm run parameter

* add simple MLP graph

* use json format for graph

* fix the tooltip index error

* frontend add graph

* optimize sampling

* fix comments

* len(data) only once