Update upgrading ruby on rails.md
Update engines.md
Update asset pipeline.md
Update AR migrations.md, fixes #59.
Sync command line md
sync action controller overview.md
Translate custom error page.
Fix a typo in front page's dd.
Update release notes (zh-TW).
Translate advanced command line.
Translate part of command line.md
Translate command_line.md (in progress).
Finish translation of command line, closes #24.
Disable autolink in example code blocks, closes #62.

Ref. http://alexgorbatchev.com/SyntaxHighlighter/manual/configuration/
Update getting_started.md
Typo in layouts and rendering
Sync upgrading ruby on rails with upstream.
Update engines.md (en).
Update engines.md(zh-TW).
Simplify contributing to ruby on rails title.