Improve EQC tests and fix bug in histogram code

The histogram code was wrong in the case where a value was the same as
the maximum allowed. Before the fix, it'd get put in in the 'Bins + 1'
bin, instead of the final bin actually used in the histogram.

The EQC tests have also been significantly improved so that error
messages from R are captured, shrinking works correctly and the property
can be tested from quickcheck directly without involving eunit.
Merge pull request #1 from basho/adt-fix-eqc

Improve EQC tests and fix bug in histogram code
Roll version 1.0.2
Add Travis CI hook and status image.
Add chat bot notification.
update rebar to 2.0.0
Merge pull request #2 from basho/dip_rebar2.0

update rebar to 2.0.0
Roll version 1.0.3