feat: new OSGiELResolver

create new OSGiELResolver which uses the OSGi ServiceRegistry to find a
service
add tests

Closes #14
test: add integration tests for OSGiELResolver

add tests, test process definitions and test delegates and behaviors
create OSGiExpressionManager
improve(OSGiELResolver): implement invoke method and add test
Merge branch 'master' into osgielresolver
refactor: refactor OSGiELResolver integration tests

create abstract superclass for OSGiELResolver integration tests
tests don't wait for deployment listener to parse the process definition
any longer, they deploy the process definitions themselves
improve(OSGiELResolver): implement methods with BeanUtils

add dependency to BeanUtils
implement methods in OSGiELResolver with the help of BeanUtils classes
chore(dependencies): Blueprint and BeanUtils as optional

mark Blueprint and Beanutils as optional in POM
remove Beanutils and Commons Collections from test environment where
they were unnecessary
improve: extract BlueprintELResolver and move Factories

-to be able to set a different ExpressionManager in ProcessEngineFactory
with ELResolver move BlueprintELResolver into new class and create
BlueprintExpressionManager
-ProcessEngineFactoryWithELResolver now takes a ExpressionManager
-change names in files
docs(README): add explanation for OSGiELResolver