Test useRef branch on react-cytoscape-js

[xhluca]

This PR should be tested before merging in react-cytoscapejs: plotly/react-cytoscapejs#53

Also add the following:

• Bump y18n from 4.0.0 to 4.0.1 react-cytoscapejs#72
• Bump elliptic from 6.4.0 to 6.5.4 react-cytoscapejs#70
• Bump ini from 1.3.5 to 1.3.7 react-cytoscapejs#67
• Bump http-proxy from 1.18.0 to 1.18.1 react-cytoscapejs#59
• Bump lodash from 4.17.15 to 4.17.19 react-cytoscapejs#54
• Bump websocket-extensions from 0.1.3 to 0.1.4 react-cytoscapejs#50
• Bump react-dom from 16.4.1 to 16.4.2 react-cytoscapejs#40

[kinimesi]

Tested and merged, closing.