Fig 0.1.13 released

[Jeff Ramnani]

Start support for Windows.

* Replaced system calls to 'tar' command with 'libarchive' gem.
* Replaced system calls to 'ssh' command with 'net-ssh' gem.
* Replaced system calls to 'mv' command with FileUtils.
* Created abstraction for executing commands in the OS module.
Previous
implementation was UNIX-specific.
* Updated algorithm for appending environment variables. Windows has
some
quirks in this area (e.g "Path" vs. "PATH")
* Added 'bin/fig.bat' to support running the RSpec tests.

NOTE: Some RSpec tests still fail on Windows and need to be fixed.