[REVIEW] Add Python 3.7 support, update to gcc5+ ABI, update dependencies: pyarrow=0.11.1, pandas>=0.23.4, cython>=0.29

[kkraus14]

NOTE: @raydouglass or @mike-wendt should merge this once the CI build matrix is ready to be updated based on this as this will break conda Python 3.5 compatibility.

Changes made in this PR:

• Adds Python 3.7 support, drops Python 3.5 support (not officially, but for now since CI is pretty tied to conda currently)
• Updates dependency versions: PyArrow=0.11.1, Pandas>=0.23.4, Cython>=0.29
• Resolves all test errors and warnings related to Python and dependency upgrades

[mike-wendt]

rerun tests

[mike-wendt]

@kkraus14

conda.exceptions.UnsatisfiableError: The following specifications were found to be in conflict:
- pyarrow=0.10 -> arrow-cpp=0.10.0 -> python[version='>=2.7,<2.8.0a0'] -> readline=6.2
- pyarrow=0.10 -> arrow-cpp=0.10.0 -> python[version='>=2.7,<2.8.0a0'] -> sqlite=3.13
- pyarrow=0.10 -> arrow-cpp=0.10.0 -> python[version='>=2.7,<2.8.0a0'] -> tk=8.5
- python=3.7

https://gpuci.gpuopenanalytics.com/job/jarvis/job/cudf/job/cudf-cpu-build/3233/consoleFull#L2,590

[mike-wendt]

pyarrow 0.11 has support for py37 but not 0.10

[kkraus14]

There's no Pandas 0.20.* builds for Python 3.7 so looks like we'll need to update that for this PR as well 🙃

[mike-wendt]

@kkraus14 building a py37 version of nvstrings for you now to help with this

[raydouglass]

There is a py37 release of nvstrings now.

[kkraus14]

There is a py37 release of nvstrings now.

Did it remove the Pandas versioning requirement?

[raydouglass]

Did it remove the Pandas versioning requirement?

Yes, there is no dependency on numba or pandas now. New version is 0.2.0

[mike-wendt]

UnsatisfiableError: The following specifications were found to be in conflict:
  - parquet-cpp -> arrow-cpp[version='>=0.9.0,<0.10.0a0'] -> libboost[version='>=1.65.1,<1.65.2.0a0']
  - pyarrow=0.11.1 -> arrow-cpp[version='>=0.11.1,<0.12.0a0']
Use "conda info <package>" to see the dependencies for each package.

will see if there is a way to fix this

[mike-wendt]

rerun tests

[kkraus14]

rerun tests

[randerzander]

fixes #118

[harrism]

Minor CXX11ABI suggestion.

Addressed changes

[mike-wendt]

rerun tests

[mike-wendt]

@kkraus14 as long as CI passes I'm nearly ready to merge. What I see missing though is an update to the README.md that explains the new flag and how to use it. Do you have anyone that can add that?

[kkraus14]

@kkraus14 as long as CI passes I'm nearly ready to merge. What I see missing though is an update to the README.md that explains the new flag and how to use it. Do you have anyone that can add that?

README updated, let me know if it needs changes.