Migrated to Bootstrap 4

[ritwickraj78]

Description

Updated the bootstrap version from 3 to 4 so that developers can now work on the latest vesion.

Fixes #449

Type of Change:

Delete irrelevant options.

• Quality Assurance

Code/Quality Assurance Only

• New feature (non-breaking change which adds functionality pre-approved by mentors)

How Has This Been Tested?

Tested locally on my system. Updating to version 4 breaks nothing.

Checklist:

• My PR follows the style guidelines of this project
• I have performed a self-review of my own code or materials
• Any dependent changes have been merged

Code/Quality Assurance Only

• My changes generate no new warnings
• New and existing unit tests pass locally with my changes

[ritwickraj78]

@abhi20161997 I have made the necessary changes. Could you please review the changes?

[abhi20161997]

@ritwickraj78 LGTM @sammy1997 Please can you have a look too ?

[sammy1997]

Still, 2 commits on this. :( Please check it

[sakshi1499]

@ritwickraj78 Can you squash and make it to one commit? We can merge then.

[ritwickraj78]

@sakshi1499 Sure I'll do the needful. And also sorry for the delay

[ritwickraj78]

@sakshi1499 @sammy1997 Seems I have pulled from the wrong branch before making the PR. So I am closing this PR and will be opening a new one. Sorry for the inconvenience.

[sammy1997]

@ritwickraj78 Yeah go ahead make a new PR. I am closing this