Merge pull request #1887 from libm/master

Better to store aws key in a separate config file.
dump symbols before stripping the nw binary
Merge pull request #1888 from libm/fix_gyp

dump symbols before stripping the nw binary
Split out aws uploader.

Since the uploader is growing big and not very much related to what the
package_binaries.py is doing, let's split it out.
Fix: cannot get HOME env in windows.