Encourage users to install the ruby-full meta-package.

* This will also install ruby-dev, which is needed for compiling any C
  extensions.
Emphasis installing ruby from the package manager.

* Most users just need a Ruby so they can run sass or jekyll.
  Whereas RVM/rbenv are more suited for developers and power-users.
Organize in-page links by installation method than by platform/tool.

* Combined the Package Management Systems sub-list into the top list.
Split the "Third party tools" section into "Installers" and "Managers".
Added ruby-build and ruby-install to the Installers section.
Added chruby to the Managers section.
Put Installers before Managers.
Add a summary to the Installers section.
Link to the chruby section.
upgrade jekyll2
removing to deprecated option
Fix title of Ruby 2.1.4 post (en)
Fix several typos in recent posts (en, ja)
Use absolute URLs in recent posts (en, ja)
Fix typos; rewrap (pt)
Translate default settings of ext/openssl (zh_tw).
Translate CVE-2014-8080 (zh_tw).
Translate 2.1.4 released (zh_tw).
Translate 2.0.0-p594 released (zh_tw).
Translate 1.9.3-p550 released (zh_tw).