Stop running when regeneration is not needed
Stop running when regeneration is not needed

When regeneration is not needed, the output less was removed.
This commit resolves this problem.
lukeapage/grunt-webfont,bjlxj2008/grunt-webfont,ryanbahniuk/grunt-webfont,sapegin/grunt-webfont,bjlxj2008/grunt-webfont,bjlxj2008/grunt-webfont,wavemaker/wavicon,georgieff/grunt-webfont2,ryanbahniuk/grunt-webfont,sdemjanenko/grunt-webfont,worder/grunt-webfont,georgieff/grunt-webfont2,BuildingConnected/gulp-webfont,wavemaker/wavicon,BuildingConnected/gulp-webfont,sdemjanenko/grunt-webfont,sdemjanenko/grunt-webfont,sapegin/grunt-webfont,ryanbahniuk/grunt-webfont,JavRok/grunt-webfont,worder/grunt-webfont,JavRok/grunt-webfont,georgieff/grunt-webfont2,BuildingConnected/gulp-webfont,sapegin/grunt-webfont,worder/grunt-webfont,lukeapage/grunt-webfont,lukeapage/grunt-webfont,JavRok/grunt-webfont