Use whitelists rather then blacklists for header and query annotations

[drpacman]

Hi Lev,
It is hard to know upfront all possible security related headers (e.g. containing authentication tokens/user info etc) which risks leaking sensitive info into Zipkin traces.

My previous implementation took a blacklisting approach. Based on the above security concerns, I now realise it is more sensible to have use a whitelist for inclusion of query params and header values then a blacklist.

[drpacman]

Hi Lev,
Good to see recent activity again on this repo. I have remerged from your updated master and resolved merge conflicts to make specific headers included. We have seen in our exploratory usage of akka-tracing that this feature is necessary as we have security credentials in headers (which vary across products) which must not be logged

[coveralls]

Coverage increased (+0.3%) to 88.18% when pulling 4c6ff8e on drpacman:master into fb4a6a1 on levkhomich:master.

[coveralls]

Coverage increased (+0.2%) to 88.112% when pulling 4c6ff8e on drpacman:master into fb4a6a1 on levkhomich:master.