[maven-release-plugin] prepare release mapdb-2.0-beta4
[maven-release-plugin] prepare release mapdb-2.0-beta4

lamfire/mapdb,codeaudit/mapdb,pettermahlen/mapdb,cocosli/mapdb,hangum/mapdb,jankotek/MapDB,jankotek/MapDB,binarytemple/mapdb,SleimanJneidi/mapdb,jankotek/mapdb,morfeo8marc/mapdb,jankotek/mapdb,ffjiao/mapdb