PR Checklist

[dsolovay]

• [x] Works with Solr 4.x, 5.x, 6.x
• [x] Works with Solr at different URLS and ports (however, file system access is required to the instanceDir root directory)
• [x] Works with all IOC options. Remove any (e.g. Autofac, see #23) that don't work. Decided to focus on Castle exclusively.
• [x] Merge sitecore/Sitecore-Intance-Manager master
• [x] Rebase to single commit (or perhaps two, one for the If logic that got added to configuration, a second for the solr install feature itself
• [x] Add Solr notes to README.md

[dsolovay]

PR submitted: https://github.com/Sitecore/Sitecore-Instance-Manager/pull/94