1.1.3.1: Merge pull request #13 from msarahan/substitute_system_cmd

Fixes a bug where wrapped scripts would fail to run if env_setup_cmd was passed as None. This is true for Conda 3.18.3 calling Menuinst. Adds default "activate" string. This should be fixed in Conda, but we'll patch it here for now to not force a Conda release.

1.1.3: Merge pull request #13 from msarahan/substitute_system_cmd

• wrap all shortcuts except "system" shortcuts in activate scripts, so that PATH will always have runtime libraries on it
• Fix out-of-date comment regarding subprocesses

1.1.1: Merge pull request #8 from msarahan/machine_string_fix

This is a minor change to make the architecture string on Windows read as 64-bit or 32-bit, rather than strings like "AMD64" which have historically confused some people about compatibility with Intel processors.