Copy a variable contents to clipit

[andrehjr]

Seems like that at some point it was possible to copy the contents of a variable. It was on the pry wiki page. (via clipit --var some_var).

[25] pry(main)> foo = :foo
=> :foo
[26] pry(main)> clipit --var foo
Error: Cannot locate: --var foo!

Ref: pry/pry#1565