update gruntfile
update gruntfile

- rename default task to build

Zauberstuhl/jsxc,diaspora/jsxc,pravi/jsxc,svbergerem/jsxc,svbergerem/jsxc,diaspora/jsxc,jsxc/jsxc,svbergerem/jsxc,Zauberstuhl/jsxc,pravi/jsxc,pravi/jsxc,diaspora/jsxc,Zauberstuhl/jsxc,jsxc/jsxc,jsxc/jsxc