Add unit test for JobStoreCenter

[andreeanica16]

1. Modify pom.xml to include all the needed dependencies
2. Modify how the ProjectLoaderStub class deals with an update. The update is added by calling the method setUpdate, that takes 2 parameters: the first parameter is a list with jobs, and only the fields that have been modified since our last call would have a value different from null. The other parameter is the list with the job in its current form, after being modified. These jobs would replace the initial ones, and so the ProjectLoaderStub would return the updated version of the job when fetching the job again.
3. Added unit test for JobStoreCenter that tests storing the information correctly to Datastore

[andreeanica16]

@iht @juliocc @tblanshard