Simple example for quantiles call from Scala.

THe commit:
 - changes QunatilesPage to inherit from Job
 - add a new example into Scala
Comments for Job API.
Polish Job API and introduce function.

- Function is lighter version of job and shares
the same API.

- Job#exec was always returning Job#DONE, so result
  value was removed. Btw: it was implicitly expected
  by the code.

- Corrected the rest of code to be compatible with API changes.
Fix h2o-scala to be in sync with current H2O API.
Merge branch 'master' of github.com:0xdata/h2o