[page] Add a solution menu webpage that can filter/sort problems by tags and/or difficulty, etc about leetcode-js HOT 4 CLOSED

1. setup github page.
2. It's better to show the solution.js directly on the website, with a clean and pretty code display plugin. Becuase solution.js are the main contents for each problem.
3. try to find an appropriate lightweight 'db' to store my leetcode problem/solutions info to display on a nice table. It needs to hv filter and sorting features.
4. Try add some lightweight css3 animations/transitions to boost user experience when using it to learn and review.

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4 Done

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2 Done

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