added 2 missing brew dependencies that broke the bootstrap.sh script.
revert changes on config.guess, the bootstrap script changed this file, perhaps shouldn't be in repo
silenced unused variable warnings.
make sure BDB_INCLUDE_PATH is in the PATH for Mac users as it can be in conflict with existing BDB installation.
merging last changes from original repository
Merge pull request #75 from gubatron/osx-env-warning-cleanups-doc-updates

OSX build documentation updates, cleanups, warning suppression.