Removed all Eclipse related files.
fully removed the eclipse .classpath file
Delete the eclipse .project file
Refactored to remove use of foldLeft/foldRight on lists. Calculator now
only uses the input list and does 1 traversal from right to left without
any addinital data structures. This is now a fully immutable
implementation 

In summary:
- Create package calculator, test
- Move Calculator to calculator, EvalTests and CalculatorTests to test
- Delete remaining irrelevant example files and worksheet
- Calculator does addition, subtract, multiply and divide
- EvalTests expand to test the operators
- CalculatorTests exist to validate input scenarios. A loophole is
discovered for a partulcar input scenario (highlighted in the test), for
which another iteration of refactoring will be required.