Add appveyor config

[vheon]

Le't go with this. For the moment I'm testing only python 2.7.9 and python 3.3.4 since are preinstalled.

If @Valloric, @puremourning, @oblitum and @micbou want to take a look would be appreciated :+1:

[micbou]

Seems fine to me.

From the documentation, python 3.4 and 3.5 are also pre-installed so you could add them.

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Reviewed 1 of 1 files at r1. Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from the review on Reviewable.io

[Valloric]

If @micbou is fine with it, I'm with it. :)

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Review status: :shipit: all files reviewed at latest revision, all discussions resolved, all commit checks successful.

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[puremourning]

LGTM too

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Reviewed 1 of 1 files at r1. Review status: :shipit: all files reviewed at latest revision, all discussions resolved, all commit checks successful.

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Comments from the review on Reviewable.io