change image path for right/down arrows

in the ddsmoothmenu js file. the `/images` file path works
fine in development but on staging and presumably production
upon pre-compilation the `/assets` works on those servers
(also in development)
redirect to using path helper

to the tagged_abstracts_abstract_path
redirect to using path helpers

for welcome_controller search action
redirect to using path helpers

for login action
redirect to using path helpers

for profiles/admin_index form
many javascript fixes

- do not load file multiple times
- ensure :remote => true works in forms
  by adding jquery_ujs file to layouts
- use rails path helper method for remote forms