config.gem implementation

I'm trying to load a gem that I've unpacked to vendor/gems from Rake,
but can't find an easy way to do it using Rails gem support. Is there
one? I do not want to add the gem using config.gem in environment.rb
because I only want to load it from a rake task.

It seems like vendor/gems would be better if it took advantage of
gem_home and gem_path in Rubygems. If it was implemented like this,
after executing :environment task in rake, I could just use:
gem "the_gem", "1.0"

It would load from vendor/gems if it's there, otherwise it would look
for it on the system.

I think it could simplify the implementation of Rails::GemDependency
too. Also, if gem_home and gem_path were set earlier in the Rails
initialization process, it would be easier to unpack RedCloth and get
the textilize method in ActionView::Helpers::TextHelper. Right now,
the TextHelper module is loaded before the gems initialization logic,
so unpacking RedCloth doesn't work. Of course, the implementation of
TextHelper could be changed - but this is just an example.



Use GemInstalller from config/preinitializer.rb and I believe all
these problems go away (let me know if they don't, and feel free to
ask/open bugs).

-- Chad