Update www/erubis pacakge to 2.6.6.

Update www/erubis pacakge to 2.6.6.

* Use lang/ruby/gem.mk instead of misc/rubygems/rubygem.mk.
* Add LICENSE.
* Remove default value of GEM_BUILD.
* Ajust new ruby package's framework.
* Add CONFLICTS since it will install the same name commands both
  ruby18 and ruby19 based packages.

- release:   2.6.6
  date: 2010-06-27
  bugfixes:

    - |
	Fixed a bug around InterporationEnhancer and FastEruby to escape back-quote. (thanks to Andrew R Jackson)

- release:   2.6.5
  date: 2009-07-20
  bugfixes:

    - |
	Fixed bug around '-z' option.

- release:   2.6.4
  date: 2009-02-18
  enhancemens:

    - |
	Rails 2.2 and 2.3 support.

- release:   2.6.3
  date: 2009-02-07
  bugfixes:

    - Enhancer name was not displayed in Ruby 1.9.1 when it was missing.

    - Command option argument name was not displayed correctly as a part of error message.

    - MethoNotFound error was raised when invalid option was specified.

- release:   2.6.2
  date:	2008-06-12
  enhancements:

    - |
	Ruby 1.9 support.

  bugfixes:

    - |
	Fixed installation problem on Windows (Thanks to Tim Morgan and Allen).

- release:   2.6.1
  date: 2008-06-06
  enhancements:

    - |
	Rails 2.1 support. (special thanks Jos\8f«± Valim)

- release:   2.6.0
  date: 2008-05-05
  enhancements:

    - |
	Improved support of Ruby on Rails 2.0.2.
	New class ActionView::TemplateHandlers::Erubis is defined and
	registered as default handler of *.html.erb and *.rhtml.

    - |
	'<%% %>' and '<%%= %>' are converted into '<% %>' and '<%= %>' respectively.
	This is for compatibility with ERB.

	ex1.rhtml:
	    <ul>
	    <%% for item in @list %>
	      <li><%%= item %></li>
	    <%% end %>
	    </ul>

	result:
	    $ erubis ex1.rhtml
	    <ul>
	    <% for item in @list %>
	      <li><%= item %></li>
	    <% end %>
	    </ul>

    - |
	'<%= -%>' removes tail spaces and newlines.
	This is for compatibiliy with ERB when trim mode is '-'.
	'<%= =%>' also removes tail spaces and newlines, and this is
	Erubis-original enhancement (cooler than '<%= -%>', isn't it?).

	ex2.rhtml:
	   <div>
	   <%= @var -%>          # or <%= @var =%>
	   </div>

	result (version 2.6.0):
	    $ erubis -c '{var: "AAA\n"}' ex2.rhtml
	    <div>
	    AAA
	    </div>

	result (version 2.5.0):
	    $ erubis -c '{var: "AAA\n"}' ex2.rhtml
	    <div>
	    AAA

	    </div>

    - |
	Erubis::Eruby.load_file() now allows you to change cache filename.

	ex.
	    eruby = Erubis::Eruby.load_file("ex3.rhtml",
		                            :cachename=>'ex3.rhtml.cache')