Changed timeline color scheme

- Draw rectangles to fill in marker colors
- Defined STEP_INTERVAL to be 15 minutes
Cleaned up line drawing process

Avoided tick function, set proper constants for step size, and wrote
drawLines function
Added SVG for timeline header
Cleanup

- Changed drawLines to drawTimeline
- Removed commented out code
Removed TIMELINE header text

Left the span in to keep the button over. I’ll remove it once I get a
little further along into implementing to the prototype
Handled add events for header_svg
Added y lines to redraw timeline function
Cleaned up row generation code, added TODO
Merge pull request #26 from ofagbemi/jf-timelineColors

Updated timeline colors
Merge branch 'master' into jf-timelineColors
Moved timeline generation into redrawTimeline
Set ROW_HEIGHT on load
Set ROW_HEIGHT conditioned on it not having been set
Merge pull request #27 from StanfordHCI/jf-timelineColors

Updated timeline colors