refactored multiple functions to work with different nodes

get_gpm, get_tanklevel, heightToGallons, heightToGallonsInTank,
and heightTOGallonsPerMinute all now take nodeId variable and
include the appropriate constants file

updated files that call these functions to include $nodeId
requiring more nodeId in more places

all MYSQL selects revised to add specific $nodeId
fixed a bug calling heightToGallonsPerMinute without $nodeId
deleted 3 old test charting files