when src files were empty, don't stop and display warning.
add a footer option, so that we can add a new line at the end of file
add footer option in the README
fixed size reporting to include banner/footer, closes #64
Merge branch 'master' of https://github.com/dsuket/grunt-contrib-uglify into dsuket-master

* 'master' of https://github.com/dsuket/grunt-contrib-uglify:
  when src files were empty, don't stop and display warning.
added test for no source files
added logging reference src that caused failure, closes #51
0.2.3