Fix deleted temporary variables and update gradle and gradle dependencies

[kulkalkul]

Updated Gradle and dependencies to up-to-date ones. I added eclipse annotations to dependencies to achieve compatibility with IntelliJ (which is the IDE I was using). There was an abstract class implementation which prevented me from compiling, I modified that. Other than that, this fixes temporary variables that are deleted during async request. I took the reference from local variables using reflection and saved it inside another hashmap, deleted it after request clears out. It is dirty, yet working. I don't know if there are any memory leaks, but there shouldn't be any I guess.

Sorry for the third mention, here is the issue related to this: #11