Summary of changes:

- Revamped the config/state system (CodaLabManager replaces config_parser).
- The BundleCLI and BundleRPCServer take the manager.
- Removed env_model; contents moved to state.json now.
- New entry point: cl.py, which includes both server and client.
- New syntax to switch client::worksheet: 'cl work dev::nlp'
- Support for aliases of addresses (including 'local').
- Ditched old config files; new ones are not compatible.
- Integrated prompting for password if trying to connect to remote server.
ensure using Python 2.7 with virtualenv
update cl.bat to use cl.py for Windows
slim down cl worker output so that printing only happens if interesting things are happening
factor out TARGET_FORMAT
Change the nature of RunBundles to make them more general and more like
MakeBundles in that we have an arbitrary collection of targets, not just a
program_target and a input_target.
Now you can type:
  cl run date
  cl program:svmlight input:wine 'program/run input output'
  cl :svmlight :wine 'svmlight/run wine output'
by default, servers open to only localhost for security
Merge pull request #11 from percyliang/master

Revamped configuration system / generalize cl run