Integrate scripts/ into installed codebase and use entry-points instead

[jchodera]

We shouldn't keep a scripts/ directory full of non-installed scripts since this makes the code hard to use on new data. Instead, we should work this code into the bitc/ source tree and make sure the modules are installed, then define entry-points in the conda meta.py or in setup.py so the user can say bayesitc ... from any location.