Fix last seen & spacing issue

[coltonhurst]

Type of change

- [x] Bug fix
- [ ] New feature development
- [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [ ] Other

Objective

This PR fixes two issues:

1. If the client is offline, the call to the API to get the config object would fail, and the "last seen" text notice would not display.
2. The last seen text notice had an unnecessary space before the colon :.

Code changes

• messages.json: Added colon to locale message
• about.component.html: Update formatting
• config.service.ts Add try / catch when call fails when client is offline

Screenshots

This is what it now looks like:

Before you submit

• Please add unit tests where it makes sense to do so (encouraged but not required)
• If this change requires a documentation update - notify the documentation team
• If this change has particular deployment requirements - notify the DevOps team