improve(test): add resize sidebar method in test utilities
improve(test): add report function for protractor

align tests with latest release 7.1.0
feat(engine): delete property

add ManagementService.deleteProperty()

related to #CAM-2215
improve(frontend dependencies): remove some unneeded files
fix(pagers): correct pagers styling
refactor: remove bootstrap-slider
refactor: remove reference to bootstrap-slider
chore(cockpit): return x.$promise instead of x.$promise.promise

related to CAM-2160
chore(webapp): do not use "help" directive

related to CAM-2157
refactor(engine/core): provide minimal engine core for BPMN and CMMN

- extract minimal engine core as base implementation for BPMN
  and CMMN
- unify ExecutionEntity and ExecutionImpl in pvm
- remove InterpretableExecution and ExecutionListenerExecution
- deprecate AtomicOperation

related to #CAM-2216