Replace whole OpenGrok based code

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Drop whole OpenGrok based codes.

Since OpenGrok based code is not designed for easy to add new feature. Drop OpenGrok based codes. And replace whole things by using modern libraries.

Use modern/reliable libraries.

• Play 2 with Scala.
• google code prettify for both analyze and render code.
• Apache Tika to detect content type.
• ElasticSearch for core search engine.
• Twitter Bootstrap for UI framework.

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This issue replaces #26, #25