kv.rb new features

Added option to parse value between brackets.
When spaces attached to a value_split ignore the spaces.
Added new feature to drill down (dig) into value and extract more key-value pairs automatically.

New test for this has been added and other tests has been changed as well to check the above changes. 
Anyway, you can also ignore the changes about "dig_values" and take the rest..
@jordansissel if its OK I can rollback them..