Fix deprecation error.

Without fix, this error message appears:

    bin/vim-ruby-install.rb:15:in `<main>': Use RbConfig instead of obsolete and deprecated Config.

    uninitialized constant Env::CONFIG
    Try 'ruby bin/vim-ruby-install.rb --help' for detailed usage.
Reformat installer.

Replace tabs with spaces. Ensure comments are properly lined up with code.
Merge pull request #153 from Ichimonji10/master

fix and reformat installer
Fix keyword symbols after parentheses

In response to the comment in #144.
Remove s:save_cpo when we're done with it
Simplify ruby*Constant syntax group matching
Highlight unicode characters in constants

Except those which are the first letter (e.g. `Ír`), as Ruby does not
recognize them as valid constants. (See also #138)
Fix constant definitions after comments.

These multi-line edge cases are almost impossible to find in the wild so I won't bother
supporting most of them for now.

Closes #164.
Merge branch 'unicode-constants' of https://github.com/amarshall/vim-ruby into amarshall-unicode-constants

Conflicts:
	syntax/ruby.vim
Missing escape() for '*'

It's escaped the first time it's used, but not the second time, causing
a regex error for the string '**'.
Merge branch 'master' of https://github.com/vim-ruby/vim-ruby