Revert "Add support for multiple concurrent execution of the same problem"

This reverts commit 9cc570397921d133e2a1bf746b282911718f6dda.
Revert "Executor first draft"

This reverts commit 145105ef4936e394b9feadb5625413d8e2f1e4a9.
Executor first draft

- Read in problemName and testcase.
- Run IPTester.
- Respond to client.
- Cleanup.

Add support for multiple concurrent execution of the same problem

- Append a uuid to problemName and save the code as problemName_uuid.java
- Search "class [ProblemName]" in code and replace with "class [ProblemName_uuid]"