Mississippi changes

1. New title: Nutrient Loads in the Mississippi-Atchafalaya River Basin
2. Changed "tool help" to  "Help ?”
3. Changed tagline to: The width of each river shows its relative contribution to nutrient loading. Show percent contributions. ( Show percentage contributions )
4. The ‘-select chemical type—’ dropdown changed to 'select nutrient type-’
5. Added Download Data button to bottom of maps and put a box around it.
6. removed pie charts button
7. moved "click on" to right