Removed existing JPA implementations and tests.

Removed existing JPA implementations and tests from the initial code drop so that the user can create them during "Step 3: Storing Order Data Using the Java Persistence API (JPA)" of the tutorial.
Removed existing MongoDB implementations and tests.

Removed existing MongoDB implementations and tests from the initial code drop so that the user can create them during "Step 2: Storing Menu Data Using MongoDB" of the tutorial.
Merge pull request #2 from matsev/issue_1

This is a fix for issue #1 "initial codeset does not correspond with guides". Thanks @matsev!