Fix for test failures. The source of this problem is the automatically assigned Date - as it is represented in ms it is very likely to differ between demo Post instanciation and parser result.
Added resources subfolder to minimise Maven output.
Removed TimelineService and related stuff because data persistence in a in-memory DB (provided by HSQLDB) was introduced. To make the persistence a little bit handier, Hibernate was added for OR mapping too.
Added tests for PostManager and introduced the TestHelper class, that should hold some multiple used logic, needed for testing.
Further cleanups, such as removing old references and adding a couple of comments. Beside that, the Follower-Followee-Relationship representing entity Follower was introduced and test cases from PostManger where adopted to create tests for FollowerManager.
Test cases are green now.
Added comments and restructured code a little bit. Although, added a Post table cleanup command to the QuickHibernateTest.
Added back sql log output in the test config. Beside that, all tests for PostPrinter and FollowerManager are green now and a couple of comments were added.
Merge branch 'feature/follow-and-wall' into develop

One can follow other users now and their posts will occur on the follower's wall. In addition, the raw-and-simple data management in Maps were replaced by data persistence in DB, using
Hibernate as OR mapper and HSQLDB (in-memory) as database.
Deleted unused / unneeded ShellTest class and added log4j + slf4j bridge + log4j.properties to disable Hibernate's noisy output.
Removed .gitkeep files because we have productive files in the resources folders now.
Added and cleaned up comments in the main/java branch.
Cleaned up and commented out the test cases.
Added more valueable content to README.md.
Merge branch 'feature/logging-and-housekeeping' into develop

The Hibernate logging output is gone now. Instead, a lot of documentation was added, edited and cleaned up.