make ci log more readable, catch matrix subclass warning

[amueller]

This should shorten the CI log a bit.
It removes a deprecation warning from the logging module, and a PendingDeprecationWarning from numpy (that can't be avoided right now because of refactoring in scipy if I understand correctly).

I removed the nose configuration as it doesn't seem needed any more.

[codecov-io]

Codecov Report

Merging #751 into develop will not change coverage.
The diff coverage is 100%.

@@ Coverage Diff @@## develop #751 +/- ##
======================================
Coverage 88% 88% ======================================
Files 36 36 Lines 4077 4077 ======================================
Hits 3588 3588 Misses 489 489

Impacted Files	Coverage Δ
openml/testing.py	96.38% <100%> (ø)	⬆️

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[PGijsbers]

Looks good, thanks!