Adding include flags for arb in CMAKE

This is perhaps not the best way, but works for me
@certik will review this once he is back from
vacation
Added `bernoulli` function

* Linked fmpq_t and  mpq_class
* Added tests.
Uodated bernoulli test to check exception if ARB is not present
Upgraded ARB from 2.1.0 to 2.2.0

This should fix issues in travis builds
Updated `bin/test_travis.sh` to link installed libraries for arb
flint