Bump dev-dependencies

[sudo-suhas]

This updates the following dev-dependencies:

• babel-eslint {8.0.0 🡺 8.0.3}
• eslint {4.7.0 🡺 4.12.1}
• eslint-config-davidtheclark-node {0.2.1 🡺 0.2.2}
• eslint-config-prettier {2.5.0 🡺 2.9.0}
• eslint-plugin-flowtype {2.35.1 🡺 2.39.1}
• eslint-plugin-node {3.0.5 🡺 5.2.1}
• flow-bin {0.54.1 🡺 0.59.0}
• flow-remove-types {1.2.1 🡺 1.2.3}
• jest {21.1.0 🡺 21.2.1}
• lint-staged {4.2.1 🡺 6.0.0}
• prettier {1.7.0 🡺 1.8.2}

eslint-plugin-node hasn't been updated due to a peer dependency.

However, flow is reporting some errors. @davidtheclark Could you please help me fix these?

[davidtheclark]

@sudo-suhas How about just leaving out the Flow update and coming back to it later? Or I can try to look at it next week.

[sudo-suhas]

Okay. I'll leave flow out of this. Please take a look when you get some time.