Optimize Summarization Algorithm for more precision

[PragatiVerma18]

Describe Problem
The summarization algorithm here doesn't summarize well in case there are smaller sentences, or there are broken sentences.

Describe the solution you'd like
We would like to have an optimized summarization algorithm such that it summarizes the text effectively without generating broken text in summary, and also is able to identify action words such as dates, days, etc, such that they're given more importance in the generated summary.

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Please submit the PR to ml branch. Once we finalize the improvements in the algorithm, we will go ahead and integrate it into the backend.