Add uniform.inv API and tests

Also added tests for previously untested uniform.pdf and uniform.cdf
functions.

PR-URL: https://github.com/jstat/jstat/pull/110
Fixes: https://github.com/jstat/jstat/issues/109
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Add documentation for uniform.inv

PR-URL: https://github.com/jstat/jstat/pull/110
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Fix documentation for exponential.inv

PR-URL: https://github.com/jstat/jstat/pull/110
Fixes: https://github.com/jstat/jstat/issues/108
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Update dist/