Update theme for Hugo v0.12 plus some fixes

- Use new `partial` call in Hugo v0.12 for partial templates
- Change `{{ .Description }}` to `{{ .Content }}`
- Enclose IE conditional comments with safeHTML function
  to prevent them from being filtered
- Minor proofreading in documentation
Merge pull request #1 from anthonyfok/update-for-hugo-v0.12

Update theme for Hugo v0.12 plus some fixes