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
Translate latest security and release posts (ru)
Merge pull request #870 from gazay/last_news

Translate latest security and release posts (ru)
Small fixes in news posts (ru)
[ja] Announce regression fix in 2.1.4 #856
Merge pull request #871 from sorah/ja-856

[ja] Announce regression fix in 2.1.4
Fix link name of Ruby User's Guide in documentation (zh_tw).

Closes #873.
Add history to 2.1.4 post (ja)
Update Ruby 2.1.4 announce with regression fix (zh_tw).
Fix typo (CVS -> CVE)