Implemented Add Conviction

Case:
(-) remove obsolete link to add convicts

datadefinition.txt
(/=) Changed model a bit to have Convicted be N:1:1 relationship.

Header:
(+) include link to add conviction

PersonSelectionServlet
(/=) make more robust, protect against invalid ids

PersonSelectionServlet, CaseServlet
(/=) rename EXTERNAL_RESULT_PERSON_ID ->
EXTERNAL_RESULT_PERSON_ID_PARAMETER for consistency

Conviction
(/=) adapt to model

CaseCreation, PersonCreation, PleaseLogin
(/=) Factored out Please Login

ConvictionCreation
(+) Functionality
(+) Basic error handling for some cases

ConvictionServlet
(+) Stub

ConvictionDatastore, ConvictionDatastoreInterface, DatastoreInterface
(+) Implement Conviction/Convicted methods needed to add convicts
Merge branch 'master' of https://github.com/vdemotz/IntroDBProject

Conflicts:
	src/ch/ethz/inf/dbproject/database/DatastoreInterface.java
Resolve Conflicts