Add github service, with getRepositories function

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Problem

We need a github service, which provides data for github integration using the current user's auth token. 2 functions are needed, getRepositories, and getIssues.

This issue handles the getRepositories function.

The function should either accept a current user as a parameter, or have the current user service as an injected dependency, to get it that way.

The function should return all repositories from the github API and return them as a collection in the format { repositoryName, githubId }.

Subtasks

• Add /services/github.js if it doesn't already exist
• Add getRepositories with described behavior to the service
• Add unit tests for the function

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This is now obsolete