Fixes #49. Support for array parameters in PDO wrapper. Adds two functions to expand array parameters (both private). One is used for the select style paramaterization, the other for the query style. While these can be combined into a single function it was more elegant, and clearer, to split them up for the different cases.
Merge pull request #50 from robotpony/pdo-array-params

Fixes #49. Support for array parameters in PDO wrapper.