Update boost-bcp to 1.54.0 version of boost.

Update boost-bcp formula to build from latest version of boost.  

In addition, drop non-standard versioning and go match boost version. This matches what boost bcp returns when running with --version.  The only problem I can potentially see with dropping the non-standard versioning is that automatically upgrading boost-bcp to the new versioning scheme doesn't work so well.  However, running "brew upgrade boost-bcp" works fine and once upgraded things should be fine.  I'd welcome comments on any better way to handle this.