Switching to Sphinx's built in JavaScript search

- disabled rST source copying, the contextual results for the search don't render, so they look goofy
- added .highlighted class to CSS for highlighting search terms
- replaced Google search form with native search form (and separated into its own theme file)
- added body class to #content div for JS highlighter to hook onto
diff --git a/user_guide_src/source/conf.py b/user_guide_src/source/conf.py
index e972a38..f68405b 100644
--- a/user_guide_src/source/conf.py
+++ b/user_guide_src/source/conf.py
@@ -167,6 +167,7 @@
 # Output file base name for HTML help builder.
 htmlhelp_basename = 'CodeIgniterdoc'
 
+html_copy_source = False
 
 # -- Options for LaTeX output --------------------------------------------------