Misc. fixes from pre-release review

[nCastle1]

This PR addresses the following issues:

• 80 - now attachment name is wrapped

• 79 - now when a file fails to launch on UWP, it should show the app picker dialog

• 77 - I'm now explicitly setting the background on the Attachments view grid; I'll need verification that this fix works, as it was already defaulting to white on my devices. I think that bug may have been triggered by Remote Desktop.

• 34 - switch to title case and fix spelling in several areas

• In identified feature popup, use Attachment with + icon in UWP to match WPF appearance
• On UWP, hide the popup close button when editing.
• Fixes issue where UWP wouldn't open attachments without a file extension

• 83 Fixes issue where the first attachment added to a feature doesn't initially display.

• Fixes issue where the 'No attachments' message isn't shown when all attachments are deleted

[nCastle1]

Merging this; note that the problems addressed by this PR have each been fixed, but the app is not yet release-worthy.