Test directory naming simplification introduces collisions

[ucbjrl]

I think the new directory naming convention introduced in #27 is a win, but we need an additional component in the name. Many (all?) of the tests are run in parallel, and the CoreSimpleTests and CoreISATests end up sharing the same directory for the rv32ui-p-simple test, and thus colliding (especially on heavily loaded systems):

[info] CoreSimpleTests:
[info] mini.CoreSimpleTests *** ABORTED ***
[info]   java.io.IOException: Cannot run program "./VCoreTester" (in directory "test_run_dir/CoreTester_rv32ui-p-simple"): error=26, Text file busy

Jenkins testing shows collisions generating the simulation source files:

In file included from VTileTester__ALLcls.cpp:3:0:
VTileTester.cpp:11516:1: error: expected ‘}’ at end of input
 }
 ^
VTileTester.cpp:11516:1: error: expected unqualified-id at end of input
VTileTester.cpp:11516:1: error: expected ‘}’ at end of input
VTileTester.cpp:11516:1: error: expected unqualified-id at end of input

[ucbjrl]

Closed by #33