Added option for BRT fitting using gbm.perf in runBRT
Added warning of the dependency on gbm 2.1-0.4, which must be manually installed from github
removed constraint for runBRT to be bernoulli in perf or gbm mode'
added arguments to runBRT for the family argument and to specify an offset if the family is Poisson
fixed mismatch between code and docs for runABRAID
Added parallel option for combinePreds (!)