Add sky_server for mac host

Add sky_server for mac host

Modified download_sky_server to choose a different sha1 file
depending on the host platform so that it downloads a correct
sky_server executable.

BUG=

[toshik, 2015-05-12 22:09:43]

toshik@chromium.org changed reviewers:
+ cstout@chromium.org, jamesr@chromium.org

[jamesr, 2015-05-14 23:47:06]

https://codereview.chromium.org/1132793004/diff/1/sky/tools/skygo/README
File sky/tools/skygo/README (right):

https://codereview.chromium.org/1132793004/diff/1/sky/tools/skygo/README#newc...
sky/tools/skygo/README:17: sky_server.sha1. If you uploaded sky_server for
linux, overwrite
can you make upload_to_google_storage.py simply overwrite the correct sha1?

[toshik, 2015-05-15 04:54:19]

https://codereview.chromium.org/1132793004/diff/1/sky/tools/skygo/README
File sky/tools/skygo/README (right):

https://codereview.chromium.org/1132793004/diff/1/sky/tools/skygo/README#newc...
sky/tools/skygo/README:17: sky_server.sha1. If you uploaded sky_server for
linux, overwrite
On 2015/05/14 23:47:05, jamesr wrote:
> can you make upload_to_google_storage.py simply overwrite the correct sha1?

We can write a script to do it automatically.
I don't think upload_to_google_storage.py should care if the uploading file is
platform dependent or not. I like the current simple behavior, which always
generates $(filename).sha1.

[toshik, 2015-05-15 18:02:02]

added upload_sky_server script

[jamesr, 2015-05-21 21:33:05]

https://codereview.chromium.org/1132793004/diff/40001/sky/tools/download_sky_...
File sky/tools/download_sky_server (right):

https://codereview.chromium.org/1132793004/diff/40001/sky/tools/download_sky_...
sky/tools/download_sky_server:17: 'linux2': 'linux',
i wouldn't add win entries and instead of checking for 'linux2' i would do
sys.platform.startswith('linux'). this means doing an if/else ladder but it
means we can print out a nicer error message if we don't understand the platform

https://codereview.chromium.org/1132793004/diff/40001/sky/tools/upload_sky_se...
File sky/tools/upload_sky_server (right):

https://codereview.chromium.org/1132793004/diff/40001/sky/tools/upload_sky_se...
sky/tools/upload_sky_server:28: upload_filename = filename + '_' +
PLATFORM_MAPPING[sys.platform]
we should share this logic with the downloader script

[eseidel, 2015-05-26 23:34:34]

eseidel@chromium.org changed reviewers:
+ eseidel@chromium.org

[eseidel, 2015-05-26 23:34:34]

I didn't know this existed and wrote https://codereview.chromium.org/1150033006/
this afternoon.  I prefer the DEPS-based approach I used, but this is also OK. 
I just tried to get out of the business of sky inventing its own way to download
files and instead used DEPS like the rest of the repo does.

[toshik, 2015-05-27 19:50:00]

Yeah, I started this CL but was not updating it in a timely manner. I think the
DEPS-based approach makes sense. Thanks for fixing it!