Allow string array in WithConnParams

[mik-volkov]

#611 This PR allows multiple parameters to WithConnParams in the form of string slice

		pgdriver.WithConnParams(map[string]interface{}{
			"search_path": []string{"foo", "bar"},
		}),

[vmihailenco]

This PR assumes that []string{"foo", "bar"} can be appended as is and does not require any quotation which might not be the case.

[mik-volkov]

Added quotation to parameters processing

[qindj]

could you please merge this? I met the same issue, thanks