Better handling of zero-length flow files Closes #819
Better handling of zero-length flow files
Closes #819

If a flow file is found to be zero-bytes:
  If there is a non-empty backup, restore the backup and resolve
  If there is no backup or it is also empty, resolve empty flow
If a flow file is found to be invalid json:
  Log and resolve empty flow

wajnberg/node-red,dbuentello/node-red,Kazuki-Nakanishi/node-red,kanki8086/node-red,Kazuki-Nakanishi/node-red,kanki8086/node-red,dojot/mashup,mw75/node-red,btsimonh/node-red,rdrm2014/node-red,Kazuki-Nakanishi/node-red,dojot/mashup,node-red/node-red,MaxXx1313/my-node-red,xively/habanero,ddm/node-red,MaxXx1313/my-node-red,giovannicuriel/mashup,dbuentello/node-red,mw75/node-red,HiroyasuNishiyama/node-red,dojot/mashup,dbuentello/node-red,augustnmonteiro/skills-visual-programming,knolleary/node-red,namgk/node-red,btsimonh/node-red,wajnberg/node-red,rdrm2014/node-red,giovannicuriel/mashup,MaxXx1313/my-node-red,btsimonh/node-red,mw75/node-red,ddm/node-red,dojot/mashup,wajnberg/node-red,wajnberg/node-red,giovannicuriel/mashup,Kazuki-Nakanishi/node-red,knolleary/node-red,knolleary/node-red,dbuentello/node-red,rdrm2014/node-red,ioglue/ioglue,namgk/node-red,knolleary/node-red,ddm/node-red,HiroyasuNishiyama/node-red,HiroyasuNishiyama/node-red,ioglue/ioglue,xively/habanero,ioglue/ioglue,kanki8086/node-red,augustnmonteiro/skills-visual-programming,ddm/node-red,giovannicuriel/mashup,xively/habanero,augustnmonteiro/skills-visual-programming,node-red/node-red,kanki8086/node-red,augustnmonteiro/skills-visual-programming,node-red/node-red,rdrm2014/node-red,MaxXx1313/my-node-red,xively/habanero,mw75/node-red