update diego api url

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
start receptor in tests that use tps

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
handle stop failures more gracefully

previously if an AfterEach had mutliple calls to StopProcess, the first
one would prevent the rest from executing, causing process to leak and
the following tests on that node to fail miserably.

now processes are stopped in batch, and their errors collected for one
final message.