DEPS: Bump numpy to 1.13.3
#25227 is trying to add `pyproject.toml` which is necessary for the whole `pip`-machinery to work smoothly post v.19.0. However, this seems to be running into problems with a numpy version bump, and mood there was to bump numpy requirement to 1.13.x.

The bare minimum for the bump is implemented in that PR, but a version bump requires getting rid of a bunch of compat code (and CI adjustments), otherwise the cruft just accumulates (it took me three PRs to clean out until 1.12).

Scipy is goint to [bump to 1.13.3](https://github.com/pandas-dev/pandas/pull/25227#issuecomment-464128057) with the next release (due to cython issues, I believe), so I thought I'll directly take it to 1.13.3 here.

I tried redistributing the CI jobs as best as I could. Here's the before/after:

**EDIT: updated pins in https://github.com/pandas-dev/pandas/pull/25554#issuecomment-475881206**

CI job: line number | before | this PR
-------|-----------------------------|-------------------
`ci/deps/azure-27-compat.yaml:10:` | `numpy=1.12.0` | `numpy=1.13.3`
`ci/deps/azure-27-locale.yaml:10:` | `numpy=1.12.0` |  `numpy=1.14.*`
`ci/deps/azure-36-locale_slow.yaml:16:` | `numpy` | `numpy=1.15.*`
`ci/deps/azure-37-locale.yaml:15:` | `numpy` | `numpy`
`ci/deps/azure-37-numpydev.yaml:18:` | `numpy` | `numpy`
`ci/deps/azure-macos-35.yaml:14:` | `numpy=1.12.0` | `numpy=1.13.3`
`ci/deps/azure-windows-27.yaml:15:` | `numpy=1.12*` | `numpy=1.13.3`
`ci/deps/azure-windows-36.yaml:12:` | `numpy=1.14*` | `numpy=1.15.*`
`ci/deps/travis-27.yaml:20:` | `numpy=1.13*` | `numpy=1.14.*`
`ci/deps/travis-36-doc.yaml:23:` | `numpy=1.13*` | `numpy`
`ci/deps/travis-36-locale.yaml:15:` | `numpy` | `numpy`
`ci/deps/travis-36-slow.yaml:12:` | `numpy` | `numpy`
`ci/deps/travis-36.yaml:17:` | `numpy` | `numpy=1.15.*`
`ci/deps/travis-37.yaml:10:` | `numpy` | `numpy`

Matplotlib needs to be bumped as well (since current min 2.0.0 cannot be resolved by conda together with numpy 1.13.3), but it's only a tiny bump to ~2.0.2~ ~2.1.0~ ~2.1.1~ 2.2.2. In any case, the version spread should probably start to reflect that there's a bunch of mpl 3.0.x about, and so I also changed the spread a bit here:

CI job: line number | before | this PR
-------------|-------|-----------
`ci/deps/azure-27-locale.yaml:9:` | `matplotlib=2.0.0` | `matplotlib=2.2.2`
`ci/deps/azure-36-locale_slow.yaml:13:` | `matplotlib` | `matplotlib=3.0.*`
`ci/deps/azure-37-locale.yaml:12:` | `matplotlib` | `matplotlib`
`ci/deps/azure-macos-35.yaml:11:` | `matplotlib=2.2.0` | `matplotlib=2.2.3`
`ci/deps/azure-windows-27.yaml:13:` | `matplotlib=2.0.1` | `matplotlib=2.2.4`
`ci/deps/azure-windows-36.yaml:10:` | `matplotlib` | `matplotlib`
`ci/deps/travis-27.yaml:16:` | `matplotlib=2.2.2` | `matplotlib=2.2.*`
`ci/deps/travis-36-doc.yaml:17:` | `matplotlib` | `matplotlib`
`ci/deps/travis-36-locale.yaml:12:` | `matplotlib` | `matplotlib=3.0.1`
`ci/deps/travis-36-slow.yaml:10:` | `matplotlib` | `matplotlib`
`ci/deps/travis-36.yaml:14:` | `matplotlib` | `matplotlib=3.0.0`

It's probably wishful thinking that everything will pass straight away (especially when mpl versions change, see the code in `pandas/tests/plotting/test_datetimelike.py`), but oh well...
