[edison-core] support parameter-names that have slashes to create structures

[ewoelfel]

Hi,

we do have parameters that are named the following way:
/some/service/subSection/config

The existing setup requires application-properties to be subSection/config which do not represent the standard way of accessing properties with structures.

I suggest introducing a separator option helping to resolve this issue.
This way our example would result in subSection.config

The PR #1210 covers this

Thanks