Getting mongo_fdw to work with libmongoc-1.0.0

I updated the project to be able to support the newest version of the mongo drivers.  The impetus behind making this change was to be able to support reading from slave replica sets, so as not to impact production with analytical queries.

Sorry about some of the whitespace issues (my text editor made some of those changes automatically).  If it is an issue, I can go through and correct them.