Replace 'render_for_text data' with 'render :text => data'

render_for_text no longer exists in Rails 3.

Fixes #955
Remove erroneous test name
When extracting attachments for an incoming message and getting the body of the main part in order to look for uuencoded text, make sure that we're getting that main part from the reparsed attachments, and not getting an obsolete attachment. Fixes #958.
Merge branch 'loop-in-cached-attachment-recreation' into rails-3-develop
Merge branch 'rails-3-develop' of ssh://git.mysociety.org/data/git/public/alaveteli into rails-3-develop
Merge branch 'rails-3-develop' into release/0.11