Remove width to make it responsive

[seth-shaw-unlv]

GitHub Issue: Islandora/documentation/issues/1105

What does this Pull Request do?

Removes the openseadragon-viewer width setting (600px) to make it more responsive.

What's new?

• Removed the openseadragon-viewer width setting (was 600px, now defaults to 100%).
• Does this change require documentation to be updated? No.
• Does this change add any new dependencies? No.
• Does this change require any other modifications to be made to the repository
  (ie. Regeneration activity, etc.)? No.
• Could this change impact execution of existing code? No.

How should this be tested?

• Make an item
• Use the Open Seadragon display helper
• squeeze your window narrow and see the window remain 600px wide
• Apply the PR
• Flush caches
• View the item again and the viewer should adjust as you change your browser window width

Interested parties

@Natkeeran, @whikloj, @dannylamb

[dannylamb]

Works as advertised