feat(engine/history): track complete scope state on act_inst

This commit adds serialization of the complete scope characteristics to
historic activity instances. Instances with complete scope characteristics
(i.e. those that consume a BPMN token and do not produce a new one) may be
queried via historic queries via #completeScope().

Related to CAM-1656
test(engine/history): add boundary act_evt tests

Related to CAM-1656
feat(engine/history): track canceled state on historicActivityInstance

This commit adds serialization of the canceled characteristics to
historic activity instances. Instance with canceled characteristics (i.e.
those that was cancelled by an interrupting boundaryEvent etc.) may be
queried via historic activity instance query viar #canceled().

related to CAM-1656
test(historic): provide a failing test case for end cancel event

relate to CAM-1761
feat(qa/perftest): add more testcases
feat(qa/perftest): sort reports
feat(qa/perftest): add image links in reports
feat(qa/perftest): add support for CSV export
fix(cycle-signavio-it): harden signavio it, update xmlunit version
feat(qa/perftest): configuration
chore(README): formatting of preamble
fix(qa/perftest): tune heap size & config
refactor(webapps/build): use grunt to build client side assets

This commit refactors the build process for camunda webapp.
From now on we use grunt to build all client side assets, manage
client side dependencies and fetch them.

Grunt is integrated into the build process via the frontend-maven-plugin.
It plugs into three phases

- in the generate-resources phase it builds client side assets and publishes
  them into the directory target/webapp
- in the test phase it tests client side assets (currently stubbed)
- in the package phase the maven-war-plugin grabs the front-end assets from
  target/webapp instead of src/main/webapp

Closes CAM-1712
Merge branch 'master' of github.com:camunda/camunda-bpm-platform