Version 0.6.0

Move the API to be referentially transparent.

API changes

Remove usage of String as currency code, use CurrencyUnit instead (#141)
Make the API referentially transparent using cats-effect (#118)
Replace twitter-utils with scala-lru-map (#125)
Migrate to circe (#119)
Move from joda-time to java.time (#123)
Drop support for Scala 2.10 (#132)
Replace mockito with specs2-mock (#130)
Bump specs2 version (#131)
Bump joda-convert version (#129)
Bump joda-money version (#124)

Build

Add code coverage reports (#144)
Add Scala version-dependent CI (#145)
Publish scaladoc (#113)
Support Scala 2.12 (#122)
Use oraclejdk8 in travis builds (#137)
Add scalafmt (#128)
Bump sbt version to 1.2.3 (#126)
Bump sbt-bintray to 0.5.4 (#127)

Miscellaneous

Update README (#142)
Extend copyright notices (#140)
Replace release badge with maven-central badge (#136)
Add CONTRIBUTING.md (#135)
Add pull request template (#134)
Add issue template (#133)
Simplify .gitignore (#121)
Remove vagrant setup (#120)
Add Gitter badge (#115)
Update README markdown in according with CommonMark (#114)