dialyzer fixes, changed newentry callback
Incompatible change to setopts

The setopts callback for probes was made asynchronous, and passes
the args (#exometer_entry{}, Options, NewStatus). A new module,
exometer_info.erl exports accessor functions (exprecs-style) to
facilitate access to record attributes without compile-time deps.

The reporter_setopts callback now receives the #exometer_entry{}
record again, since race conditions could result from fetching
it in the reporter process.
added functions + docs in exometer_info
Merge pull request #90 from Feuerlabs/uw-dialyzer-fixes

dialyzer fixes, changed newentry callback
fix doc on exometer_entry setopts callback
regenerated docs
added bounded highnum retention for histograms
fixed docs on starting exometer
make highest values follow sliding window
Merge branch 'uw-histogram-accuracy'
Change exo repository
Merge branch 'master' of github.com:voluntas/exometer