[test.elliptic-cg-discretization] removed obsolete virtual
[test.elliptic-testcases] updated spe10 header
[test.elliptic-sipdg-discretization] updated expected results, refs #2
[test.elliptic-swipdg-discretization] update

Use up to date testing framework, updated la backend and updated expected
results.

refs #2
[products.base] add compute_locally()
Merge branch 'master' of https://github.com/pymor/dune-gdt