Fix a bug in sampling from the prior
Revert "Fix a bug in sampling from the prior"

This reverts commit 064a3df1c37ade09c6ebc05196f5d61c2fa6d4fe.
Added prior argument to the posterior mixture weights.
This resolves an issue with data where negative controls have all zero counts.
Udpate vignette
Update doc and description to use knitr rather than sweave. Depend on R 3.0
update doc
recompile doc
fix makefile