refactor walkByExpansion to return pointer
call getRecourceFrom in a goroutine
pass waitGroup as parameter instead of global definition
cleanup logs and time measurements
increase efficiency by limit expansion to the fields that are in filter
remove unneccessary pointer parameter of
Merge pull request #1 from chrisport/master

Parallelization and limiting expansion
add LRU cache for resolving data
add expiration to cache-entries
add tests for caching and expiration
add documentation for Cache
Merge pull request #2 from chrisport/master

Caching HTTP-Calls
add check in getResourceFrom - @eluleci
Not exiting if a problem happened in makeGetCall
minor fix
add mutexes for concurrent access to result-map and cache
Revert "add mutexes for concurrent access to result-map and cache"

This reverts commit bfdde378256f6c98e8d1080ca1998a02cade8570.
Revert "Revert "add mutexes for concurrent access to result-map and cache""

This reverts commit bdc27e8afb890cb733d728f9785c9627ce067e0b.
ops - @Ferit
- add timeout to connection to external ressources
- move definition of connection timeout in config
ops - @Ferit
- remove parallelization, since it can fail _sometimes_
- validate filter, because invalid filter leads to infinit recursion
ops - cleanup parallelization garbage
replace empty []interface{} with []struct{} this prevents it from being replaced by 'null' in json's Marshall-method