LP#1424815: Cleanup/simplify perl and template

LP#1424815: Cleanup/simplify perl and template

This commit attempts to cleanup and simplify the "Read more" catalog
feature by making the following changes:

  - Simplify perl util function
    - Remove extra blank lines
    - Remove first IF branch, since rindex already covers this case
    - Remove "rest" from return value, since Kathy's changed stopped
      using it
    - Add logic to address the FIXME comment
    - Add a few code comments

  - Simplify template
    - Only split a string if feature is turned on in config settings
    - Allow, but don't require, "trunc_length" on every marc note field
    - Add a few code comments

Signed-off-by: Remington Steed <rjs7@calvin.edu>