Removing duplicate distribution tests

Test group for binomial pdf was exactly duplicated

PR-URL: https://github.com/jstat/jstat/pull/107
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Prevent overflow error in centralF pdf

Use the algorithm found in the R source to calculate the centralF pdf,
which avoids large exponentiation and hence doesn't suffer from NaN
overflow errors.

Fixes: https://github.com/jstat/jstat/issues/100
PR-URL: https://github.com/jstat/jstat/pull/107
Signed-off-by: Trevor Norris <trev.norris@gmail.com>
Update dist/
Now working on 1.0.9