[Torch] Move test.lua to the top level

Summary:
This removes some CMakeLists.txt manipulation.

Test Plan:
```
luarocks make rocks/nn-scm-1.rockspec && th -lnn -e "nn.test()"
...
Completed 710 asserts in 81 tests with 0 errors
```
Merge pull request #110 from ajtulloch/move-test-to-top-level

[Torch] Move test.lua to the top level