Update contribution guide to mention possible ffi dependencies for Ubuntu
Update contribution guide to mention possible ffi dependencies for Ubuntu

Fixes #755

denisKaranja/jasmine,GerHobbelt/jasmine,songshuangkk/jasmine,wongterrencew/jasmine,martinma4/jasmine,IveWong/jasmine,qiangyee/jasmine,suvarnaraju/jasmine,martinma4/jasmine,marcioj/jasmine,kyroskoh/jasmine,antialias/jasmine,aln787/jasmine,morsdyce/jasmine,deborahleehamel/jasmine,suvarnaraju/jasmine,antialias/jasmine,IveWong/jasmine,James-Dunn/jasmine,kidaa/jasmine,tsaikd/jasmine,GerHobbelt/jasmine,rlugojr/jasmine,WY08271/jasmine,negherbon/jasmine,soycode/jasmine,James-Dunn/jasmine,tsaikd/jasmine,Sanjo/jasmine,caravenase/jasmine,negherbon/jasmine,marcioj/jasmine,tsaikd/jasmine,seanlin816/jasmine,imshibaji/jasmine,xolvio/jasmine,seanparmelee/jasmine,morsdyce/jasmine,morsdyce/jasmine,danielalexiuc/jasmine,SimenB/jasmine,qiangyee/jasmine,caravenase/jasmine,kalins/samples-javascript.jasmine,JoseRoman/jasmine,caravena-nisum-com/jasmine,xolvio/jasmine,songshuangkk/jasmine,James-Dunn/jasmine,aaron-goshine/jasmine,mashroomxl/jasmine,IveWong/jasmine,rlugojr/jasmine,yy8597/jasmine,Contagious06/jasmine,leahciMic/jasmine,denisKaranja/jasmine,denisKaranja/jasmine,James-Dunn/jasmine,IveWong/jasmine,jnayoub/jasmine,kidaa/jasmine,faizalpribadi/jasmine,deborahleehamel/jasmine,WY08271/jasmine,Contagious06/jasmine,seanlin816/jasmine,Jahred/jasmine,morsdyce/jasmine,mashroomxl/jasmine,aln787/jasmine,caravena-nisum-com/jasmine,Muktesh01/jasmine,faizalpribadi/jasmine,Muktesh01/jasmine,songshuangkk/jasmine,soycode/jasmine,Contagious06/jasmine,imshibaji/jasmine,Sanjo/jasmine,seanlin816/jasmine,paulcbetts/jasmine,suvarnaraju/jasmine,tsaikd/jasmine,xolvio/jasmine,yy8597/jasmine,Jahred/jasmine,SimenB/jasmine,kyroskoh/jasmine,caravena-nisum-com/jasmine,caravenase/jasmine,leahciMic/jasmine,SimenB/jasmine,caravena-nisum-com/jasmine,negherbon/jasmine,leahciMic/jasmine,faizalpribadi/jasmine,rlugojr/jasmine,soycode/jasmine,seanparmelee/jasmine,Muktesh01/jasmine,GerHobbelt/jasmine,songshuangkk/jasmine,kyroskoh/jasmine,kalins/samples-javascript.jasmine,denisKaranja/jasmine,Jahred/jasmine,wongterrencew/jasmine,deborahleehamel/jasmine,kidaa/jasmine,martinma4/jasmine,deborahleehamel/jasmine,denisKaranja/jasmine,kyroskoh/jasmine,yy8597/jasmine,wongterrencew/jasmine,Muktesh01/jasmine,danielalexiuc/jasmine,SimenB/jasmine,JoseRoman/jasmine,faizalpribadi/jasmine,seanlin816/jasmine,WY08271/jasmine,kalins/samples-javascript.jasmine,aaron-goshine/jasmine,wongterrencew/jasmine,JoseRoman/jasmine,soycode/jasmine,antialias/jasmine,Muktesh01/jasmine,WY08271/jasmine,seanparmelee/jasmine,jnayoub/jasmine,suvarnaraju/jasmine,deborahleehamel/jasmine,qiangyee/jasmine,rlugojr/jasmine,negherbon/jasmine,morsdyce/jasmine,aaron-goshine/jasmine,kyroskoh/jasmine,yy8597/jasmine,leahciMic/jasmine,jnayoub/jasmine,yy8597/jasmine,imshibaji/jasmine,Sanjo/jasmine,mashroomxl/jasmine,kidaa/jasmine,marcioj/jasmine,imshibaji/jasmine,Contagious06/jasmine,songshuangkk/jasmine,JoseRoman/jasmine,marcioj/jasmine,antialias/jasmine,GerHobbelt/jasmine,paulcbetts/jasmine,xolvio/jasmine,aln787/jasmine,paulcbetts/jasmine,Jahred/jasmine,aaron-goshine/jasmine,rlugojr/jasmine,kidaa/jasmine,seanparmelee/jasmine,seanparmelee/jasmine,qiangyee/jasmine,James-Dunn/jasmine,marcioj/jasmine,suvarnaraju/jasmine,seanlin816/jasmine,kalins/samples-javascript.jasmine,negherbon/jasmine,Sanjo/jasmine,SimenB/jasmine,GerHobbelt/jasmine,martinma4/jasmine,danielalexiuc/jasmine,caravenase/jasmine,caravenase/jasmine,mashroomxl/jasmine,Jahred/jasmine,faizalpribadi/jasmine,aln787/jasmine,tsaikd/jasmine,aln787/jasmine,antialias/jasmine,wongterrencew/jasmine,WY08271/jasmine,JoseRoman/jasmine,aaron-goshine/jasmine,leahciMic/jasmine,danielalexiuc/jasmine,xolvio/jasmine,imshibaji/jasmine,jnayoub/jasmine,paulcbetts/jasmine,jnayoub/jasmine,caravena-nisum-com/jasmine,Contagious06/jasmine,mashroomxl/jasmine,kalins/samples-javascript.jasmine,IveWong/jasmine,martinma4/jasmine,Sanjo/jasmine,danielalexiuc/jasmine,soycode/jasmine,paulcbetts/jasmine,qiangyee/jasmine