renamed servlets to servlet, refs #95
added our own persistence exception, ref #87
Merge pull request #96 from przytads/95

renamed servlets to servlet, fix #95
Merge pull request #97 from przytads/87

added our own persistence exception, ref #87
add csarDetail template refs #75

introduced AbstractServlet

the CsarDetailsServlet implementation is fast/dirty
it should show concepts and problems of the current state
baseline for further discussions