Remove eunit from default target

Two remedy this, two new targets are added:

- eunit: Run EUnit tests
- test: Run EUnit and QC tests
More aggressive shrinker for choose/2

The old shrinker would simply subtract one from the current value, which
was ineffective when shrinking large ranges (e.g. choose(0, 16#ffffffff)).
This new shrinker converges towards min by repeatedly halving the
difference between current value and min.
Increased level of randomness

The Erlang random number generator does not have an high level of randomness because it is based on a default seed and the result is that each Triq run generates the same random values.
I have created a triq:generate_randomness/0 function which uses crypto to improve the randomness and it is invoked in triq:check/3 which (if I am not wrong) is the function that finally checks a property.

So Triq now generates random values with a different seed for each property.
Merge pull request #32 from MirkoBonadei/increase_randomness_level

Increased level of randomness
Add travis
Remove verbose seed output
disable breaking test
Make pdict test be run as eunit
Fix travis yml
Add travis build graphics
Make the pict test a bit more verbose on error
Merge pull request #31 from jhlywa/master

More aggressive shrinker for choose/2
Merge pull request #30 from nifoc/makefile

Remove eunit from default target
Make triq_tests runnable again