Rename views: _*.rhtml to _*.erb and *.rhtml to *.html.erb

As partials might also be used in js formatted responses, we just
rename them to .erb. Normal templates are renamed to .html.erb.
This follows the new Rails convention to play well with tilt.

for i in `find app/views/**/_*.rhtml`; do \
  git mv $i `echo $i | sed s/\\.rhtml$/.erb/`; \
done

for i in `find app/views/**/*.rhtml`; do \
  git mv $i `echo $i | sed s/\\.rhtml$/.html.erb/`; \
done