Replace 'array_to_query_form' with 'Array#join'
Use 'Enumerable#map' in 'fix_arrays'
Extract 'Util.convert_array_values'

The 'fix_arrays' method is of more general nature than the Connection
class. Move it to the Util module, and give it a bit more descriptive
name.
Merge pull request #7 from jvirtanen/cleanups/refactor-code

Refactor code