Add Highlight feature
Cleaned up highlighting, lint fixes

- Added a test.html for easier testing
- Made the highlighting more in line with the line number removal
functionality (use responseDiv).
- Also only needed to make the width of the td.line-data element 100%,
thus saving a lot of jQuery manipulation.
- Fixed some lingering issues with linting such as a global ‘head’
variable, and mixed double vs. single quotes.
- Changed line to lines
Updated README for v 1.5
Merge pull request #17 from blairvanderhoof/pr/16

Pr/16