Bump default Ruby to 2.0.0
Add <Leader>h/<Leader>H for Ruby 1.8->1.9 hash syntax.
Fix ctags support in Vim.
Upgrade pathogen for Vim.
Update syntastic.
Enable Ruby syntax checking via Syntastic.

Intentionally block JRuby and Rubocop from loading since they really
slow things down. (Rubocop is really only slow because rbenv is loading
the bundled version, so even the check for Rubocop version is slow.)