Update to latest LeanKit.API.Client
Updates to github connection to catch auth issues

When connecting to github it only validates the username/password is
valid, it doesn't check the repo is valid. So once you try to retrieve
projects (repos) if the repo is invalid it fails silently. Updated the
code to throw and catch so it will show an error in the UI.
Fixed LK polling frequency. Passes the configured polling frequency to LK API Client. Fixed broken tests.
Upgrading nuget packages
Updating LK API Client
merged from master