Add docker build

[joshmoore]

I recently ran into an issue opening n5 from zarr. I figured this repo was a good place to start to figure out what's going on. I'll see if I can make a change that makes that test fail. In the meantime, this is the setup I used to build locally. Note that there are a few failures:

  /opt/conda/envs/z/lib/python3.7/site-packages/pyn5/file_group.py:228: UserWarning: Expected N5 version '2.0.2', got 2.1.3; trying to open anyway
...
FAILED test/test_read_all.py::test_correct_read[read z5py zarr using zarr, gzip] - OSError: Not a gzipped file (b'x^')
FAILED test/test_read_all.py::test_correct_read[read zarr N5 using z5py, gzip] - RuntimeError: Exception during zlib decompression: ...
FAILED test/test_read_all.py::test_correct_read[read zarr N5 using z5py, raw] - assert False

[joshmoore]

I found my issue. The sub-attributes.json files are missing "n5": "2.0.0". Moving this back to tischi/i2k-2020-s3-zarr-workshop#1

[jakirkham]

anaconda is a weird metachannel, which isn't really intended for public use. conda-forge should be higher priority than defaults as that is how conda-forge packages are built and intended to be used.

Suggested change

	channels:
	- defaults
	- ome
	- conda-forge
	- anaconda
	channels:
	- ome
	- conda-forge
	- defaults

[jakirkham]

conda-forge packages of both of these exist. That said, do we need pre-commit? Is this environment intended for development or just testing?

Suggested change

	- pip:
	- pre-commit
	- pytest-qt
	- pre-commit
	- pytest-qt

[joshmoore]

Sorry. This is a copy of the ome-zarr-py dev environment. Thanks for catching it.

[constantinpape]

Thanks @joshmoore. I think the failures you see are because I haven't merged #7 yet.
I will try to look into this soon and then also look at this PR, but let's focus on the issue with the missing attribute first.

[joshmoore]

Updated based on @jakirkham's feedback and added a github workflow.

[joshmoore]

Doh. I hadn't seen #12 -- Happy to rollback those changes, but https://github.com/constantinpape/zarr_implementations/actions/runs/361203107 now represents what I'm seeing locally.

[constantinpape]

@joshmoore this looks good. I am merging and deprecating #12.
I will try to fix the test failures in a separate PR.