if type of field is Map or Set, then get serializer from its declared generic type
add countColumnFields to count how many fields which has @Column
serializer should infered by generic type if field's type is Set and has no @Serializer
add FooSet field for testing
without magic number
polish
get generic type by index
support mapping custom type to map value
change how Set element store. If there is any dots in element's value (toString) to Set, then mapping won't work correctly.

Signed-off-by: center56 <center56@cc.ncu.edu.tw>
change how Set element store. If there is any dots in element's value (toString) to Set, then mapping won't work correctly.
Merge branch 'CustomTypeSetMapSerialize' of ssh://git@github.com/yyc1217/astyanax.git into CustomTypeSetMapSerialize
change the way that how Set stores its elements.
Merge branch 'CustomTypeSetMapSerialize' of https://github.com/yyc1217/astyanax.git into CustomTypeSetMapSerialize