Revision 240

+ Fixed problem with build paths for python tests being in the wrong location
+ Added build & run for python unit tests for escript and finley.

NOTES
+ scons defaults to building ALL targets so if will build everything, including running all tests. This behaviour can be modified by specifying the DEFAULT targets but I've not done this yet. In the interim specify the target you want.
+ Some dependencies need to be specified as scons does not figure them out automatically, though a helper scanner might be able to. These can be specified explicitly using scons Depend function. Not yet done so you can get an invalid build (especially in parallel). Examples include python depends on shared libraries, possibly a couple of library dependencies for install targets - need to verify.