Unable to link to existing github repository
Hey team!

First off, love this software and looking forward to using it!

### Description

Unable to link to existing repository. I have setup and pushed to a repository once with the application, but decided I wanted to move this to a more local directory to the software I work with. This is a private repository. When I select Repository > Repository Settings, I am presented with either Publish a new repo to my org on Github, or signing into an Enterprise server. What I would like to do is enter an existing repository URL and link these two up.

### Version

Showing on version [0.1.12](http://kactus.io/release-notes/).

**Kactus version:** 0.1.12

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**OS version:** OSX 10.11.6 El Capitan

### Steps to Reproduce

1. Click Repository
2. Click Repository Settings...
3. Attempt to link to an existing private repository on Github.

**Expected behavior:** I expected to be able to link to an existing private repository.

**Actual behavior:** I was only able to publish a new repository.

**Reproduces how often:** 100% of the time.

### Logs

[2017-07-21.kactus.production.txt](https://github.com/kactus-io/kactus/files/1166748/2017-07-21.kactus.production.txt)
