fix to workspace/current endpoint

[MarkThorley]

Purpose

This PR closes issue #10

Current behaviour

Currently retrieving the current workspace filename will return a blank if the file hasn't been saved prior.

New behaviour

Puts some default values in if the filepath retuns an empty string

Implementation

n/a

Known limitations & dependencies

n/a

Declarations

Check these if you believe they are true

Codebase

• [/] The code base is in a better state after this PR
• [/] Is documented according to the standards and ready for inclusion with release notes.
• [ ] User facing strings, if any, are extracted into *.resx files

Testing

• [/] The level of testing this PR includes is appropriate
• [/] The solution has been compiled, loaded and tested in current Dynamo version (1.3)
• [ ] All tests pass using the self-service CI (if present).

Changes

• [ ] Snapshot of UI changes, if any.
• [ ] Version change follows Semantic Versioning and is updated in the assembly DLL version.

Reviewers

Reviewer 1 @radumg