Allow Apache thrift or fbthrift

[theopolis]

There are two commits here:

• Using a clean, Vagrant-built, copy of facebook/fbthrift, using thrift1 to compile the Python interface using the osquery-python thrift specification. Copy that output into the new directory osquery/extensions/fbthrift. This effectively accomplishes nothing because that module is unused.
• Use the osquery.extensions.fbthrfit module as osquery.extensions when importing from . This requires a cleanup of the generated code in 1 place where the import osquery.extensions. form is used, which does not respect the sys.modules list.

The goal is to use whatever version of thrift is found first. Essentially try for fbthrift's module and fall-back to Apache.