bfast package consolidation

Thanks to pull #1, we have an opportunity to consolidate all the changes across the different forks of bfast, with a view of eventually updating the package on CRAN.

For ease of reviewing and consolidating code, it would be nice to have collaboration across the different code authors on a single codebase. GitHub supports this somewhat, using protected branches so that the code does not conflict/does not get lost.

Suggestions about how best to go ahead with this are welcome!