When MRI, change rendering engine of markdown (kramdown -> qiita-markdown)

[sue445]

Why?

qiita-markdown is better than kramdown in markdown rendering

Example

Sample markdown

• https://gist.githubusercontent.com/sue445/a0d3f9e5177b2801fb41/raw/2e93016c2d74a8c99fdcbd0f4f607a1fe6446cf4/test.md
• https://gist.github.com/sue445/a0d3f9e5177b2801fb41

Before (Use kramdown)

After (Use qiita-markdown)

Breaking changes

• If use qiita-markdown, requirements ruby2.x+ 😿
  • qiita-markdown support only ruby 2.x+
    • https://github.com/increments/qiita-markdown/blob/v0.8.0/qiita-markdown.gemspec#L19
  • jruby can not build charlock_holmes (dependency of qiita-markdown)

[seratch]

Dropping CRuby 1.9 is fine but I'd like to avoid dropping JRuby becuase users especially in China are running Gistub on the JVM. Using kramdown instead when JRuby is preferred.

[sue445]

Using kramdown instead when JRuby is preferred.

I see.

I changed implements at 3e872f6
Use both qiita-markdown(MRI) and kramdown(JRuby)

Please check again 🙇

[seratch]

Thanks. LGTM.

[sue445]

😍

[lukehorvat]

Hi @seratch, could you release a new version for this? Thanks.