Scholar profile without image can be registered.

Closes #42 (closed)

Short description of what this resolves:

Resolved the problem of registration of scholar profiles without an image.

Changes proposed in this pull request:

• Replace /citations/images/avatar_scholar_128.png with https://scholar.google.com/citations/images/avatar_scholar_128.png

Checklist

• My branch is up-to-date with the Upstream develop branch.
• The acceptance, integration, unit tests and linter pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)