Check for Windows OS or JULIA_COPY_STACKS on jcall, improve testing

[mkitti]

Squashed commit of the following:

commit 8dbbcdc
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Fri Mar 6 21:29:18 2020 -0600

Enable JULIA_COPY_STACKS=0 on mac

commit b9b89ee
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Fri Mar 6 19:43:35 2020 -0600

Reduce testing

commit 21b0198
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Fri Mar 6 17:58:42 2020 -0600

Configure forced async tests

commit c9c3051
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Fri Mar 6 17:39:43 2020 -0600

Don't expect exception on Windows

commit 2df1c84
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Fri Mar 6 17:29:35 2020 -0600

Create new environment test flags, check async fail on windows

commit 56abdf6
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Mon Feb 24 03:35:43 2020 -0600

Include but allow to fail linux @async case with JULIA_COPY_STACKS=0

commit 0c0279c
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Mon Feb 24 03:14:16 2020 -0600

Do not initialize using @async on Windows

commit dfc4aea
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Mon Feb 24 03:05:19 2020 -0600

Test JavaCall under @async

commit 7ebf526
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Mon Feb 24 02:26:55 2020 -0600

Streamline Travis configuration, include Windows

commit bc2431d
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Mon Feb 24 01:39:05 2020 -0600

JULIA_COPY_STACKS should not be recommended or asserted on Windows

commit 59973a3
Author: Mark Kittisopikul mark.kittisopikul@utsouthwestern.edu
Date: Tue Feb 18 11:23:49 2020 -0600

Assert root Task for jcall and jfield

[mkitti]

JULIA_COPY_STACKS=1 does not seem to work well on Windows, so we should not recommend setting that environmental variable on that operating system.

[mkitti]

Users are finding that JULIA_COPY_STACKS=1 does not work on Windows:
https://discourse.julialang.org/t/problem-in-running-julia-on-juno/35412/2

[aviks]

Is there any change needed to the documentation based on this PR?

[mkitti]

I added some documentation for using JavaCall on Windows.