Modernize install-julia.sh for CI and drop Julia v0.5

[rdeits]

I noticed that many of the Travis builds were failing, and I suspect it might be because the install-julia.sh script is using outdated Julia download URLs. This should update the download URLs to their new homes.

I also noticed that this script accepted download/win32 etc. as arguments, but (a) their URLs were also out of date and (b) if those URLs existed, the script would have done nothing with them on windows and tried to feed a windows .exe directly into tar on linux. So I've just deleted those arguments. Please let me know if you want them back.

[rdeits]

I've also dropped Julia v0.5 on appveyor since it's no longer supported by PyCall.jl

[rdeits]

Ok, I've made some progress on this. I had to mark the v0.7 tests as allowed failures, since PyCall doesn't work with v0.7. It looks like there's also an existing problem with some of the v0.6 builds on windows: https://ci.appveyor.com/project/Keno/pyjulia/build/1.0.45/job/4eg7o7bh7fh7t6cu#L159 which existed previously: https://ci.appveyor.com/project/Keno/pyjulia/build/1.0.35/job/d6gu3c898kma3jid#L95

[tkf]

I added a one-line fix in #161 for appveyor. @rdeits Can you pull 20e3c71 ? (BTW, thanks for all the fixes!)

Or the maintainers can pull #161 so that this PR would be automatically closed as well. Either way, I'm happy as long as the CI is up :)

[rdeits]

@tkf thanks! I've pulled in 20e3c71

[rdeits]

Ok, all checks are passing. Good to go?

[tkf]

In osx build with PYTHON_VERSION=py3, it looks like Python 2 is used instead of 3: https://travis-ci.org/JuliaPy/pyjulia/jobs/373733201#L256

[tkf]

I tried to fix it in #163. But it turned out python3 is not installed with current .travis.yml:
https://travis-ci.org/JuliaPy/pyjulia/jobs/380045548#L262

Actually, brew list python &>/dev/null || brew upgrade python outputs nothing:
https://travis-ci.org/JuliaPy/pyjulia/jobs/380045548#L79
...so it means brew in travis cannot install Python 3?

I'm not familiar with brew so I think I'll not try to fix it further.

Anyway, I think this PR is better be merged, even without solving this problem.

[tkf]

Actually, I think now I solved it in #163!
https://travis-ci.org/JuliaPy/pyjulia/jobs/380511380#L2638

[rdeits]

Great! I'll close this in favor of #163