feat(spring): add support for spring process apps

- add SpringProcessApplication and SpringServletProcessApplication for
  supporting process application bootstrapping using spring.
  #CAM-446

- add support for defining a managed process engine inside a spring
  process application context xml file. The process enigne bean must be
  constructed using the new
  org.camunda.bpm.engine.spring.container.ManagedProcessEngineFactoryBean
  #CAM-445

- add support for Spring Expression Resolving in process applications
  through
  org.camunda.bpm.engine.spring.application.SpringProcessApplicationElResolver
  #CAM-444
chore(it): revert arquillian config
chore(spring): fix maven dependency scope
Merge pull request #5 from camunda/spring

feat(spring): add support for spring process apps

* add SpringProcessApplication and SpringServletProcessApplication for
supporting process application bootstrapping using spring.
#CAM-446
* add support for defining a managed process engine inside a spring
process application context xml file. The process enigne bean must be
constructed using the new
org.camunda.bpm.engine.spring.container.ManagedProcessEngineFactoryBean
#CAM-445
* add support for Spring Expression Resolving in process applications
through
org.camunda.bpm.engine.spring.application.SpringProcessApplicationElResolver
#CAM-444