Update classpath

Add App Engine Java testing utilities to `.classpath` file.
Merge branch 'enable_sdk_tests'
Add getKey test to program test
Upgrade App Engine SDK to 1.8.8

Upgrade the App Engine SDK to the latest version (1.8.8). This commit
basically just changes some JAR files in `war/WEB-INF/lib`.

Developers working on the application after this commit are expected
to have version 1.8.8 of the App Engine SDK installed, and have
Eclipse configured to use it.
Upgrade App Engine testing utilities to 1.8.8

Update the classpath to use the App Engine testing utilities for
1.8.8.

For more information on the App Engine Java testing utilities, see:
https://developers.google.com/appengine/docs/java/tools/localunittesting#Java_Introducing_the_Java_testing_utilities
Refactor program getKey test

Refactors the program getKey test to use a new AppEngineTest base
class.

After this commit, new test classes should inherit from AppEngineTest
when they require the use of App Engine SDKs, like the
PersistenceManager.
Add getKey test for the student entity
Test UserCreator
Test Authenticator
Test ProgramCreator
Test ProgramFinder
Test StudentFinder
Test StudentCreator
Test StudentEnroller
Test ProgramViewer
Test ProgramIncomeViewer
Merge pull request #25 from fantastic-five/more_tests

Test use cases
Merge pull request #27 from fantastic-five/sync_environments

Upgrade App Engine to 1.8.8
Fix error while attempting to view nonexistant program
Handle validation errors while creating programs