deal.II 8.2 (new formula)

Added support for deal.II library with numerous dependencies
and options.
The build is parallel unless you say `ENV.deparallelize`. For the test, I think you can determine the number of cores with `Hardware::CPU.cores`:
````
$ brew irb
==> Interactive Homebrew Shell
Example commands available with: brew irb --help
irb(main):001:0> Hardware::CPU.cores
=> 8
````
(ps: `brew irb` is mighty cool!)