Automatically fills Go default values

[jiangz222]

If insert document with field of slice type without initialization, filed will be null in MongoDB, which may cause operation error(e.g. $push to null error).
Qmgo can initial fields to default value as mgo does.
We can Implement this in package field.

[lifegit]

excuse me, can you tell me how to use it?

[lifegit]

install slice is null, hope []

[lifegit]

@jiangz222 worry... thanks ！