updating to rebar 2.5.1
changing hardcoded coverdata file path in

https://github.com/rebar/rebar/blob/e9f62c45807ce2db39e0606c4d97cd071416bd64/src/rebar_cover_utils.erl#L250
fixing location for ct.coverdata and modules
Merge pull request #14 from marcelog/marcelog_rebar_2.5.1

Updating rebar to 2.5.1, fixes for R17