Performance issues in capslayer/data/datasets/cifar10/reader.py

[DLPerf]

Hello,I found a performance issue in the definition of __call__(self, batch_size, mode) ,
capslayer/data/datasets/cifar10/reader.py,
dataset = dataset.map(parse_fun) was called without num_parallel_calls.
I think it will increase the efficiency of your program if you add this.

The same issues also exist in dataset = dataset.map(parse_fun) ,
dataset = dataset.map(parse_fun),
dataset = dataset.map(parse_fun)

Here is the documemtation of tensorflow to support this thing.

Looking forward to your reply. Btw, I am very glad to create a PR to fix it if you are too busy.