Migration jcrown

Opening this pull request for discussion and review purposes, there is still MUCH to be done!!!!

migration.py is a sample of how we can use the library to perform the actual migration
ftpmirror.py takes care of recursive download via FTP. It would probably make sense to organize it a little bit better (like putting it in a class), as well as adding a recursive upload method, which would allow us to upload the stuff to the destination server, hence avoiding the tarball (this seems pertinent since untarring might be a pain on some setups).

TODO's
- MUCH more error checking!
- search and replace of old file paths in files and database
- separate the WP specific stuff from the general use stuff
- figure out how to organize our plugin repo (see the plugin_update_jcrown branch for the source of the plugin), as of right now migration.py is just blindly assuming that the zip file for the plugin is in the same directory.
- Possibly use MD5 has instead of file size to ensure that the downloaded file was not corrupted in any way.