Extracted RCP product into bootstrap bundle which checks Java version

Problem: if the bundle that defines the RCP product requires a higher
Java version than the version of the current runtime, then the bundle is
not resolved and the application does not start and shows no message to
the user at all.

Solution: extract the product definition into a bootstrap bundle that
can always run with Java 6, check for the version and, if necessary,
show an appropriate message to the end user.

Issue: #196
Merge branch 'master' into feature_java8
Changed compiler settings to Java 8
Java8: use collections streams API
Fixed delete transaction quick fix to use correct delete method
Java 8: use try-with-resource
Fixed field declarations hiding another field
Replaced custom Files utility class with Java 7 version
Extracted deleteTransaction to default interface method
Added predicate containsTransaction to period
Merge branch 'master' into feature_java8
Enabled language selection via the preference page
Fixed NPE in SecurityPosition
Check if PP is running in development mode
Moved translated labels to bootstrap bundle next to Application.e4xmi

Issue: #196
Update travis-ci configuration to use Java 8
Updated README.md to Java 8
Improved English translation (hopefully)
Added option to excluded 'without classification' from taxonomy charts

Issue: #173
Updated sonar configuration to skip feature project