Update README.md

Anyone interested in maintaining ruby-processing at processing-1.5.1 instead of seeing it move to processing-2.0. The following having all forked ruby-processing.
'@aviflombaum', '@Epictetus', '@jandot', '@reaktivo', '@roovo', '@allant', '@fjenett', '@alx', '@NevenaDjaja', '@hbzhang', '@gravitystorm', '@visualisierte', '@originalsurfmex', '@sunnybythesea', '@DekusDenial', '@abachman', '@joannecheng', '@monkstone/graphs', '@monkstone/fork', '@fo60213', '@yush', '@peterkrenn', '@endymion', '@fcoloni', '@monkstone', '@davidxv', '@nicksieger', '@macdiva', '@designtestcode', '@tegatai', '@ahastudio', '@michaelforrest', '@jexchan', '@maxhawkins', '@dhaas', '@tbueno', '@ybakos', '@prezjordan', '@Rakasha', '@andilar', '@macournoyer', '@monkstone/pulse', '@benkant', '@cjapes', '@hassyx', '@phren0logy', '@maxehmookau', '@imageoptimiser', '@bassnode', '@murasesyuka', '@moumar', '@jurisgalang', '@naehrstoff', '@sergheim', '@tonytargonski', '@utgarda', '@ejjoo', '@arubis', '@mjording', '@aaajiao', '@mathpunk', '@rubypoet', '@daveyoon', '@martinstannard', '@jashkenas', '@onehouse', '@peterbenoit', '@dhf2001', '@BEATLES-OC', '@weirdpercent'