[test] AbstractService: Test for stateLog access as normal user

This test currently fails and therefore exposes a bug in the access
control logic of the AbstractService.
[Assets] Add 'dave' account, a conference owner
[test] AbstractService: Test for stateLog access as conf admin

User dave is neither abstract owner, nor site admin, but a
conference owner. As such he currently is denied to get the state
log, although he should be able to get it. Thi is issue  #186.
[service] Abstract:SL: use isOwner instead of owners.contains

This commit fixes the issue that abstract  owners (which are not
site admins) cannot access the abstract stateLog, because
owners.contains(account) did not find the account even though
it should have . isOwner converts the collection returned by JPA
into a scala Sequence and then uses contains. That works as
expected. See also issue #86.
[service] Abstract:SL: conference owners are also allowed

This closes issue #186
Merge pull request #196 from gicmo/stateLogFixes

Fix stateLog access for owner and conf. owner
[service] Abstract: apply() has now implicit request param

Fix all locations where request was not marked as implicit yet and
an AbstractService was created.
[service] Conferences: apply() has now implicit request param

Fix all calls without an implicit request in the package
controllers.api.Conferences()
[service] Figure: apply() has now implicit request param
[utils] DBUtils: functions now take an EntityManagerProvider

The EntityManagerProvider is the encapsulation object to get
the EntityManager. db{Query, Transaction} now take an
implict EntityManagerProvider to get the EntityManager from.
Change all Service classes + PermissionBase to provide that
implicit parameters. Fix tests as well.
This is the first major step to recycle EntityManagers.
Cleanup some imports
[utils] DBUtils: Don't close the EntityManager

Since we want to recycle EntityManager we must not close it.
[utils] Requests* are now EMPs and carry an EntityManager

We create an EntityManager in both, the AccountAwareAction and
the AuthenticatedAction and have the corresponding requests
carry them around. After we invoke the action's block the
EntityMangers are closed again. This is the next major step to
recycle EntityManagers.
[utils] DBUtils: new EntityManagerProvider.fromRequest()

Helper method to obtain an EntityManagerProvider from a request.
If the current request is indeed an EMP just return ist, otherwise
create a EMP from the DefaultPersistenceUnit.
[service] PermissionBase inc. valide() into setPermissions()

Inside setPermissions() we are already in an open transaction. If
we call validate() from within that transaction we will try to create
another one. This is unnecessary, but will also stop to work if we
re-use EntityManagers across dbTransactions.
[service] Abstract: Use EntityManger from request
[service] Conference: Use EntityManger from request
[service] Figure: Use EntityManger from request
[service] UserStore: move implicit EMP var into functions
[service] UserStore: findAccount: pass EMP implicitly