Better support for .erb comment blocks

[Vuneu]

Expected behavior

<% 
=begin %>
  <p id="notice"><%= notice %></p>
  <h1><%= content %></h1>
<% 
=end %>

Actual behavior

<%# <p id="notice"><%= notice %></p>
<h1><%= content %></h1> %>

[wingrunr21]

This is resolved by #260 as the code between the start and end <% %> tags will be detected as Ruby (and thus the =begin and =end block comment syntax will work).

[wingrunr21]

This should be fixed now