removing splitArgs

Obviously , tasks must be delimited by colon from arguments ,
 and taskName don't need to have colon itself. 
<code>task : args:other_args:etc_args , </code>
but(!) no
 <code>Some:Not:Readable:task :args</code>
So , it will be more lightweight code in lib/util/tasks.js 
and taskNames will be more readable.