MNIST package not found in the examples

[abianco88]

Some of the example scripts in the examples directory (like ae.jl, mnist_full.jl, mnist_simple.jl, etc.) don't run. They return the following error message:

ERROR: The following package names could not be resolved:
 * MNIST (not found in project, manifest or registry)
Please specify by known `name=uuid`.

It seems the issue arises because the MNIST package doesn't exist anymore. @oxinabox mentioned that said package

has been replaced with MLDatasets but the examples and docs need to be updated

That may certainly be true for ae.jl, which presents a using MNIST statement at the beginning, but I'm not sure it's also the case for mnist_simple.jl and mnist_full.jl. In fact, both include("mnist_loader.jl"). which in turns is using MLDatasets rather than using MNIST, so I'm not sure what's causing the error. Any help will be greatly appreciated.

---

If you are making a bug report, please copy and paste the output of the following Julia snippit into the issue:

using TensorFlow
tf_versioninfo()
Wording: Please copy-paste the entirely of the below output into any bug reports.
Note that this may display some errors, depending upon on your configuration. This is fine.

----------------
Library Versions
----------------
Trying to evaluate ENV["TF_USE_GPU"] but got error: KeyError("TF_USE_GPU")
Trying to evaluate ENV["LIBTENSORFLOW"] but got error: KeyError("LIBTENSORFLOW")

tf_version(kind=:backend) = 1.13.1
tf_version(kind=:python) = 1.13.1
tf_version(kind=:julia) = 0.12.0

-------------
Python Status
-------------
PyCall.conda = false
Trying to evaluate ENV["PYTHON"] but got error: KeyError("PYTHON")
PyCall.PYTHONHOME = /home/admin/anaconda3:/home/admin/anaconda3
pip --version = pip 19.3.1 from /home/admin/anaconda3/lib/python3.6/site-packages/pip (python 3.6)

Trying to evaluate pip3 --version but got error: Base.IOError("could not spawn `pip3 --version`: no such file or directory (ENOENT)", -2)

------------
Julia Status
------------
Julia Version 1.0.5
Commit 3af96bcefc (2019-09-09 19:06 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i7-7700T CPU @ 2.90GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, skylake)