release version bump [ci skip]

release version bump [ci skip]

release version bump [ci skip]

release version bump [ci skip]

pre-release version bump

pre-release version bump

fix: HikariCP configuration

when both jdbcUrl and dataSourceClassName are set, dataSourceClassName has the higher priority during setup and
it requires setting all the necessary related properties. HikariCP will not validate config (newly fixed, see [1])
and silently initialize an 'empty' data source which fails during runtime. this fix drops the usage of jdbcUrl,
and properly and fully sets the data source properties.

[1] brettwooldridge/HikariCP#401

prepare release

switch to java 8

since java 7 reached end of life, we migrated to java 8. from now on we require jdk 8 to build and run. in the near future, we will slowly change/update the code base to make use of java 8's features