Fixed issue with multiple scan conditions in scan request producing duplicate items
Try converting number value to Long on attribute update first (before converting to Double)
Improved code for scan() when scanning with conditions

Moved common code to separate methods
Implemented proper number/string comparisons for all comparing operators (GE, GT, etc)
Various small fixes to make code behave more like actual DynamoDB (i.e., only apply CONTAINS to strings)
Added unit tests from rev 984508 and a1a095 to v2 test classes