README: add to limitations section
classes consisting of static methods should not offer public constructor
pom: add name as per "Sonatype OSS Maven Repository Usage"

see also:
https://docs.sonatype.org/display/Repository/Sonatype+OSS+Maven+Repository+Usage+Guide#SonatypeOSSMavenRepositoryUsageGuide-5.Prerequisites
pom: remove link to project page form description

(project/url already provides this)
[maven-release-plugin] prepare release 0.4.0
[maven-release-plugin] prepare for next development iteration
pom: advance master to 0.5.0-SNAPSHOT

The branch '0.4.x' has been created for maintenance of release 0.4.0