Implement hands on hp-view-graph

[jovnc]

Exercise Review

Exercise Discussion

#54

Checklist

• If you require a new remote repository on the Git-Mastery organization, have you created a request for it?
• Have you written unit tests using repo-smith to validate the exercise grading scheme?
• Have you tested the download script using test-download.sh?
• Have you verified that this exercise does not already exist or is not currently in review?
• Did you introduce a new grading mechanism that should belong to git-autograder?
• Did you introduce a new dependency that should belong to app?

[damithc]

@jovnc Closing this PR, as you already have other hp-* PRs. Thanks for the PR nevertheless. It will still be useful as a reference to others.