fix disconnect error handling when raise_error is not set

If connection to server failed, redis comands throw exception, while
desired behaviour when raise_error is not set is to return error object.
see #14
add testcase for no raise_error and make it pass
add no_raise_error_1.pl example. see #14
bump version 2.21_01
require perl 5.12 on Windows

on 5.10.1 tests hang on Windows as reported by @chorny. fixes #15
bump version 2.22