Remove unused class

[#74337848]
Rename BulkApps to BulkAppsController

To match its filename and CC conventions [#74337848]
Extract bulk api config out of controller

So a controller does not have class methods, this is unconventional [#74337848]
Extract StagedAppsQuery before modifying it

So it is easier to write a unit test for just the query [#74337848]
Exlude apps without a detected start command

In Diego an app can get marked as STAGED before its start command is known
causing a race between the bulk importer in nsync and the desired app message.
By exluding apps without a start command the bulk apps importer will never
see an app before it is actually ready to be started [#74337848]

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>