update bmon to 2.1.1-pre1

the version 2.1.1-pre is the newest one that can be compiled in OSX.
P.S.  bmon's latest version is 3.1 ,but it cannot be compiled in OSX because of lacking the dependency libnl(this one is depend on linux header files).
Should the homepage be updated to http://www.carisma.slowglass.com/~tgr/bmon/ ?