Support getting size of pasted script in cli.

[DylanPiercey]

Was thinking I often find myself needing to calculate the minified size of some arbitrary script I found on the internet.

It would be awesome to be able to:

jsize --verbose
# [PASTE SCRIPT]

   Initial  Minified  Gzipped
  
   271 kB   88.6 kB   30.8 kB

[antonmedv]

If we will have support for files #49 we can use stdin: pbpaste | jsize

[DylanPiercey]

Ah yes that'd be perfect.