Marking test_look_at_neural_V1 memory intense

[deirdre-k]

test_look_at_neural_V1 is running out of memory in Travis, causing tests to fail (see #917) with the following error:

FAILED brainscore_vision/model_helpers/generic_plugin_tests.py::test_look_at_neural_V1[resnext101_32x8d_wsl] -
RuntimeError: [enforce fail at alloc_cpu.cpp:75] err == 0. DefaultCPUAllocator: can't allocate memory: 
you tried to allocate 102760448 bytes. Error code 12 (Cannot allocate memory)

This PR marks the test memory_intense, meaning it will only be run in Jenkins

[mschrimpf]

re-trigger jenkins