Iterate demo page header style

Description

This pull-request improves the style of the Headers on the demo.html. It puts the main title and header information in a Bootstrap 'jumbotron'. The spacing could be improved in a follow-up iteration. Additionally the boarder spacing is changed to use Bootstraps 'container' spacing.

Related Issue

https://github.com/JustinGOSSES/wellio.js/issues/52 Duplication of demo page between wellio & wellioviz?

Motivation and Context

This change improves the audience viewing experience of the demo.html.

Types of changes

[ ] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

[ ] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[ ] I have added tests to cover my changes.
[X] All new and existing tests passed.

Note: Test run:

Load a las file
Convert the las file UWI displays Curve Headers display Clicking on a Curve Header attempts to display visually, but fails (same behavior as before)

Let me know if this change could be accepted (or rejected) or needs some additional changes before being approved and merged.

Thank you, DC

JustinGOSSES / wellioviz