Mead story figure changes to SVG

[jordansread]

• [x] Limit to users with average annual use above 15,000 AF
• [x] for pictogram chart, Change x-axis to: “Lower Colorado River Water Entitlement Holders”
• [x] Below this on axis, clarify with “with an Average Annual Consumptive Use above 15,000 acre-feet”
• [x] Change y-axis to: Average Consumptive Use 2010 to 2014
• [x] Add text in legend that disassociates the location of the boxes with a location on a map within a state. Suggested language: location of blue boxes does not represent location of water use.
• [x] For Mexico, always show as 1.5 maf in the graphic
• [x] Label teacup as “Lake Mead”
• [x] million acre feet shown at bottom of reservoir does not need to be written out, as ‘maf’ is already indicated
• [x] Flood Control Surplus starts at elevation 1,200 feet to be consistent with 24-Month Study graphic (Label as a range “Above Elevation 1,200 feet)
• [x] text at top of reservoir blue box should show a range of elevations

[jordansread]

all but "Add text in legend that disassociates the location of the boxes with a location on a map within a state. Suggested language: location of blue boxes does not represent location of water use." should be covered in #431

[jordansread]

@eread-usgs curious if the un-checked one up there can be in the caption or if it needs to be in the SVG itself?