Refactor for React/Redux and pagination improvements

New Features

UI

• Added styles to buttons
• Added current and total count for neighbor nodes
• Hide pagination controls if there is only one page of adjacent vertices

Internals

• Refactored application to use React and Redux
• Rearranged folder hierarchy to match React pattern with containers and components
• Using react-router working with hashes.
• Added CSS loaders to webpack configuration
• Added Pure.css for styling
• Added markdown linting with markdownlint