use https rubygems in test gemfiles
Check for Rails::Railtie specifically
documentation: combining object reference and class attribute
Add tests for downlevel-revealed IE cond comments
Implement downlevel-revealed IE cond comments

Enable creation of "downlevel-revealed" IE conditional comments:

    /![if !IE]
      A comment

Will produce

    <!--[if !IE]><!--> A comment <!--<![endif]-->

or if :conditional_comments_valid_html is false:

    <![if !IE]> A comment <![endif]>
Fix typo in Coffeescript documentation.
Documentation fix for preserve
Merge branch 'master' of https://github.com/Pringley/haml
Merge branch 'https_rubygems' of https://github.com/teeparham/haml
Don't produce invalid html with html_attrs

The html_attrs method produces the attributes xmlns, xml:lang and lang.
Of these only lang is valid in HTML 4, and the other two are unnecessary
in HTML 5.

Change html_attrs to only produce xmlns and xml:lang elements if the
format is xhtml.
Don't generate MS-style conditional comments

Remove option to allow generating MS-style conditional comments, only
generate the valid HTML style.
Document downlevel-revealed conditional comments
Merge branch 'conditional-comments-bang-ie'
Add `--remove-whitespace` option to the CLI

Sets the `remove_whitespace` option to `true` for the engine,
effectively stripping all whitespaces (including linebreaks).
Fix typo in exec.rb

"whitespace" not "whitespaces".
Return nil from capture id result isn't a String

Rail's capture helper returns nil if nothing is written to the buffer
and the result of the block isn't a String.

Change Haml's helper to match this behaviour.

Fixes #439
Return nil from capture id result isn't a String

Rail's capture helper returns nil if nothing is written to the buffer
and the result of the block isn't a String.

Change Haml's helper to match this behaviour.

Fixes #439
(cherry picked from commit 754ac46ec73cb8a6cbeee0f5ceba77439237ebd9)
Check for nil in Rails 3.0
Check for nil in Rails 3.0
(cherry picked from commit ccfcd6497f8ee093408c297023141b665d08459d)
Pin Nokogiri to 1.5

Nokogiri 1.6 doesn't build on Ruby 1.8.7.