Changes to support Jekyll 3

[rearrange]

Github Pages is now updated with Jekyll 3 --- and there are little changes and upgrades need to be done for this theme to support it. See this upgrade link

Since this theme is based from Poole, the changes suggested here is the same as per commits for Hyde. Basically, 3 items:

1. Disable relative_permalinks as it breaks example content.
2. Adds the missing jekyll-paginate gem to remove the depreciation message.
3. Change markdown and highlighter to use default Jekyll 3 (supported for GitHub Pages) --- kramdown and rouge (instead of pygments and redcarpet).

[ariestiyansyah]

Cool, thanks for the update. Let me check it fisrt before merge.