The original fix for issue #7 used sed and didn't update the `executable` check
from cat to sed. This patch uses String.gsub when parsing an erb file instead,
as sed isn't neccesarily available.
Many of the syntax checkers were setting the 'bufnr' key for each
error manually and one was setting 'text' if it didnt exist too.
Add the 'defaults' option to SyntasticMake to set default values in the
returned error list - it only sets values if they are empty.
Rails 3 ships with its own version of Erb. Plain old Erb barfes on things like
<%= form_for ... do %> instead of old <% form_for ... do %>
For the moment, let's use sed to filter out this case. Dirty kludge, but that
will do for now.
