POM Warning Fixes

Fixed the following warnings:

> [WARNING] Some problems were encountered while building the effective model for org.trifort.fixeddb:fixeddb:jar:1.0.0
> [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-javadoc-plugin is missing. @ line 99, column 15
> [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-source-plugin is missing. @ line 86, column 15
> [WARNING] 
> [WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
> [WARNING] 
> [WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
> [WARNING] 
> [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!